My iso/cso files are not working! why?

My custom firmware is 3.52M33-4 and when i download iso/cso files, it gives me a .rar file and then when i extract the rar file, it gives the name of the game.iso but in a rar archive. I dragged that .iso rar archive into my psp but it doesnt work and there isnt a iso/cso file. When i go in the .iso rar archive all i see is PSP_GAME folder and UMD_DATA.BIN can someone help please? thanks