What DAW are you using?
Place a De-Esser on the vocal tracks, it gets rid of that harsh SSSS and T sound when sung.
In terms of fixing the dynamic range, if you insert a compressor into the chain, it automatically controls the dynamic range.
Play the track at roughly a part where you think the vocals are at a comfortable level and set your threshold so it just starts compressing at that level.
The ratio is how much compression is applied, so 3:1 would mean that for every 3dB over the threshold, the output of the compressor will only be 1dB over the threshold limit. I don't find it uncommon to use a ratio of 7 or 8:1 for vocalists with a huge dynamic range.
Attack and Release are just how quick the compressor reacts to the sound going over the threshold and you should control that completely to taste.
The vocals are very mid-centric sounding for me (a lot going on between 2-4Khz), if you cut about 2-3dB in that region, they should sound more natural and should allow you to turn them up to sit in the mix better.
Guitars sound great. If you add a small hall reverb to everything, it should also allow it to blend in better!
If that's one of your first mixes then well done, it's far better than anything I had achieved in my first recordings!