First of all, as you're new to recording I think you should take the word 'Master' out of your vocabulary, that is if you are planning doing everything the DIY route. Mastering requires a number of things including:-
-A trained ear, this comes with years of experience of recording/mixing
-A really good monitoring setup
-The ability to master in a different room
And much more besides. I like to consider what I do to my songs 'polishing'. I'm not experienced enough or skilled enough(nor do I have the things I mentioned earlier) to say I master my songs. However, this polishing process consists of exporting my finished mix(which has to be EXACTLY the way I want it) and putting it through a compresser, limiter and maybe also EQing it. All of this will add some gloss to the song. I'm not saying DIY mastering can't be done, a number of people do it but for somebody new to recording(as you are) - it's gonna be a lot further down the road. There are lots of stuff you can read, and lots of knowledgeable folks here who can tell you much more than I can about mastering