If your using an SD card forget about the .dol file. Until someone elde says otherwise it is not necessary to play the games. Next you put the boot.elf on the root along with a folder called roms. Your roms will go in here. Make sure they're unziped or the ii can't read them.
As for finding roms it is not permited to tell someone on the forums, but using Google should get half-decent results. If you can't find a good site PM me and I'll send you a link for one I use. I DO suggest trying your own first though.
Best of luck. :)