New Ubuntu user trying to compile program

Hi guys, new to Linux/Ubuntu - lifelong Windows/DOS user (sorry :/)

I have a program for mining Steem installed (www.steemit.com). I followed a guide to install this, it worked; but the guide didn't explain what any of the commands actually did.

They have just updated the source code and I need to upgrade to 0.12.2 https://github.com/steemit/steem/releases

Can anyone tell me how I install this so it actually works? xD

Thanks!!