need more help, playing isos on psp slim firmware 3.71

ok i got a psp slim with firmware 3.71, i have also bought a 2gb mem stick, could someone point me in the right direction.
what i need is my psp to run these isos with no risk to the console and preferably no more money.
i need this console to still be able to interact with other psp’s and run games, surf the net, watch movies, etc. (dont no if this will affect those aspects)
please post ur answers in simple, idiot proof and with links plz –
Answer #1
U need to install custom firmware to play the games that u have downloaded from internet.
Here is complete noob guide-
http://www.pspiso.com/showthread.php?t=140243
Though pspiso will require u to register first before seeing that page.
cheers.
Answer #2
thanks, ill have a look @ it, i hope it works, im dying 2 download some games and play them on it
EDIT: is this telling me that i cant install it cause i have a psp slim, its saying that i cant downgrade the firmware.
im also unsure to what the term “pandoras battery”, plz explain