Depending on your goal, there are a few ways to do it.
#1 You could mic everything. Vocals, Guitars, Drums, and Bass <or direct in for the bass>. Run say six or seven mics into a mixer. Then in the mixer you mix it to left/right stero. Then run the Stereo signal into the computer. That would allow for a "live" type recording. Some think that this way is the best so you can acheive a live or real type sound. For this you only need one stero in. MOST disagree on this way since at this point, in the computer you cannot edit the channels or tracks seperatly. You are limited to all the instruments together and this makes it tougher for overall sound quality and it takes a band being TIGHT TIGHT to not have to rerecord it everytime one person misses a note.
#2 Another way to record live would be to mice everything, and then run it into an interface that will take say 8 inputs. This would allow you to record everything live onto seperate tracks to be able to edit and mix later. For this you would need say 8 inputs. This is a better way than the first, but still not good. This way you will hear all the noise and bleeding over from everyones playing and instruments. More flexiblity but still noisy.
#3 Another way would be to mic say the drums first, run that stereo into the interface, and record a stereo track. Then play that back into headphones for the bassplayer to hear a play along with recording the bass on a different track solo. Then you can mix those together into some headphones for some rhythm guitar and record it and so on. This is the way most songs are recorded. This way gives you the cleanest tracks for each instrument and the most flexiblity to edit and eq, add compression ect later. To do it this way you only need the card I use. With stereo I/O's. The card itself will play unlimited tracks, and you can record left and right at the same time.
Let me know if that helps or not, I'm sure other's could add or correct me.
SpaceBoy