Simple custom nameplates

[Ethly]

I'm trying to figure out how to replace Blizzard's enemy nameplates with my own ones. I know how to create frames, but I can't understand how to hook my frames, so they will replace Blizzard nameplates. Is there some article or simple addon I can look into? I tried to read Blizzard_NamePlates.lua but it seems that there's too much going on there. I need some simple code to start, just simple colored rectangle would be more than enough, then I can tinker from there.