will someone help me get started?

ok, for starters, i downloaded PJ64 along with mario kart 64 and bomberman arcade roms (and i do own both). but the problem is, how do i proceed from there? my roms appear to not be in a supported file type, and i do not see how to unzip them (if nescessary) please help me!
both roms are in the format 7z and PJ64 appears to supports a lot of formats... .zip,.?64, .rom, .usa, .jap, .eur, and .bin. is there any conversion software that i need? or did i just download bad roms? where can i download working ones, if so?
thanks a lot and i hope someone can help me get this working.

um... i dont know even how to use this forum, i cant seem to find my thread XD

i have no problem unzipping anything else... i do it w/ nes roms all the time...

someone? i really want to figure this out, please respond!