You have one big option/decision to make and that is whether to use your mixer. To my thinking there are two reasons you might want to use it:
A - If you want to leave some things hooked up all the time, like a line out from your guitar amp or pod, Audio line output from a keyboard, and or audio output from an electronic drum module or some such. With the mixer you can have these wired up all the time and just move the sliders up and down to have access to them.
B - If you want to record more than two things at once.
If neither of those applies, then for now I'd say put the mixer on a shelf and just work with the Mbox Mini. Either way, the connections for the Mini are the same:
1 - On the back of the Mini there are two 1/4" outputs labelled "Monitor Out". These need to get routed to the Red and White RCA jacks on the back the left monitor. (The monitors should have come with a wire for connecting the right speaker to the left speaker. It will connect to the red and black push tab connectors on each speaker). Now since you have 1/4" outs on the Mini and RCA ins on the monitor you need adapters. You can get what you need at Radio Shack or online. There are two options - adaptor cables that have a 1/4" plug on one end and an RCA plug on the other. These will work very nicely. alternatively, you can get plug adaptors that have a 1/4" plug on one end and a female rca jack on the other. These basically convert a 1/4" output to an RCA output. Then you use a normal RCA cable pair to connect from there to the monitor inputs. I like the adapter cable solution a little better, because there's just the cord to worry about, but either setup will work just fine.
2 - You to run the standard USB cable that came with the Mini from its port on the back of hte mini to a USB port on your computer.
3 - You plug your headphones into the headphones jack on the front of the Mini. You may need an adapter here too if your headphones have an 1/8" plug or if you are using earbuds. A simple 1/4" Male to 1/8" Female jack adapter can be had at Radio Shack to solve this problem.
4A (No Mixer) - Now, If you are not planning to use the mixer, you plug your microphone into the mic jack on the back of the Mini and whatever other couple of instuments you want to use into the Line in/DI jacks using standard 1/4" Instrument Cables. You can use TRS cables, but good quality standard cables should work just fine. Line 1 and the Mic share a single actual input to the computer. You select which one you want to use by pushing the little Mic/DI button just down and to the left of the mic input (looking at the back of the unit). Note that for both inputs there's a -20dB button on the back of the unit (it is labelled 'Pad'). Use this if your source signal level is high. You will know this if you have to have the gain knob on the front panel really low to get the right recording level in your software. For your mic or for most instrument outputs these would not be engaged. Finally, on the back panel there is one more button labelled 48V. For your current Mic, you want this button out. If you ever buy a condenser mic that calls for "Phantom Power" you'll click this button in to provide power for the microphone. Kindof important note. Turn your speaker volume all the way down whenever you click this button in or out because it might create a really loud "pop". Also, whenever the button is in, do not plug in or unplug the microphone. Turn 48V off, wait a few seconds, plug or unplug the mic, then turn it back on.
4B - (With mixer) If you do want to use the mixer, you'll want to run a pair of 1/4" instrument cables (or better yet TRS cables) from the Main Outs on the mixer to the 1/4" Line 1 and Line 2 Ins on the back of the Mini. You'll click the Mic/DI button IN, to select Line 1 rather than the mic input. Depending on what mixer you have you may or may not want the 'Pad' buttons In, but whichever it is you will want them both the same way (both in or both out). You want the 48V button out, as you aren't going to use the mic input at all. You didn't say which Xenyx mixer you have. I think they all have 1/4" main outs, but if by chance it only has RCA outs, you'd do the same thing you did for connecting the monitors 1/4" to RCA cable adapters or jack adapters. Now you plug your microphone and instruments into the mixer and away you go. You'll want to set the gain knobs on the Mini to the same level for each channel and adjust them so that you get proper recording levels when you mixer output fader is sitting somewhere near zero. Before making this adjustment you'd adjust the channel trim on the mixer so that the mixers output meter shows peaks at just below zero or occasionally touching zero with the channel fader set at zero (12 noon if the channel fader is a knob). Important note - when I say channel fader at zero, I mean 0dB gain according to the scale along side the slider knob. That will be about 3/4 of the way up, not all the way off. If you find that to get all this lined up the gain knobs on the mini have to be turned really low, click in the 'pad' buttons. This will let you turn them up to the middle of the range. Once you get this all set, leave those gain knobs alone and manage your signal levels at the mixer.
It think that's about it... Have fun and feel free to ask more questions. If anybody sees anything I've gotten wrong, chime in (as if anybody that knows is actually gonna read all this! Ha!
J
PS - I haven't addressed configuring your computer to see and talk to the mini. That's a little beyond what I can explain here, but here's a link to the getting started guide that will explain all this. It's way ProTools slanted, but the basic process should be the same for whatever software you want to use.
http://www.google.com/url?sa=t&sour...oq30Cw&usg=AFQjCNE5DsLxxRkcFgTEPdua0cihfuD6iw
, dunno what to do.