First thing is first. Inside the custom recovery make sure to select "Backup" and make a backup of your phone before you first flash a new rom. That way if things go wrong you can restore to this point before you made any major tweaks.
Once you have that done. Head on over to XDA by clicking the button below. It has a huge selection of custom roms to choose from. Just make sure any rom you do flash is specifically for the D801 or is designed for any variant of the LG G2
This page was designed as my final submission to CSE322 -JG. Any information gathered here about tweaking your phone is merely an abstract of what needs to be done. Do your research and you and only you are responsible for what happens to your phone.