Well I'll give you answers....
Do u need CFW to put ISO/CSO files on ur psp?
Yes you do.
and how do u put them on?
Specifically? Just make an ISO folder called ISO in the root of your memory stick which is next to the folder named PSP and MP_ROOT. Then throw the file (iso) in there.
i have 3.80 ofw. can i put them on my psp or do i need cfw?
No because you need CFW.
and if i can how do i put them in?
Answered that in the first question.
Yeah if you want to downgrade to 1.5 then upgrade to a custom firmware to use isos then this is the best site for you.
Oh and btw, some isos have alot of MB's almost a gig half the time, depending on what they removed from the game to make it into an iso. I was just wondering how many MB or GB you have?