Here's my dumbed down simple version: Send each sound to its own bus on the mixer and turn the volume on each down completely. Then slowly bring up your drums, snares, etc listening to make sure no sounds over power the others. Then bring up the instruments making them sit in the mix. Once everything sounds alright, add some dynamics like reverb on some of your instruments, stereo, eq, look up some of these words on Youtube for basic tutorials. The general idea is you dont want your music to sound like it feels like your drowning in mud. You want it to sound crystal clear and make it pop!