cant connect to virgin mobole towers with a gs5 cm12

Hello. I recently came to the solution in order to fix my phone I needed WO wipe everything on including the system. Oops. I still had twrp on my phone, thank god. I was able to flash over a cm 12 (lolipop) ROM. I installed my g apps and everything's working great. EXCEPT, that I can't connect to any tower, I'm cut off. I dont no what it is, I think its because when I wiped my phones system, I wiped virgin mobile clean off it. I was messing with the APN settings, but I don't have one clue on what I am doing, I am a newbee, and I have no idea what Odin and that stuff is. I got myself in this mess, anyone can help?