Help!!! New and confused

Hi everybody. I am new here and its all a bit confusing. I am not even sure which forum I should be posting in.
I have an original PSP and have official firmware 3.71 from the sony site. I have recently downloaded a game as an eboot. I placed this on my memory card and recieved a "software protection is invalid" error.
I have looked it up on the net and downloaded custom 3.71. I placed this in my UPDATE folder and it would not work.
I have looked into this on the net and it all seems so complicated to me with all the different kernels etc. Is there any way I can change my official firmware to a custom one that will allow me to play eboots that I doanload.
If anybody can help can they please explain it in simple terms as I new to this.
Many thanks

You need a homebrew compatible firmware to go to custom FW. (1.50).

I am not upto date with the new ways, but ive heard Pandoras battery can be used to downgrade.

Search the forum about downgrading with pandora battery.

It will take you a while and you need to research first. (just to warn you).

(btw, this goes in the Psp help section, just so you know were to put your next psp querry.

try here http://www.freewebs.com/dsmultiplay/index.htm

If you wanna be safe from all the hassle
you can buy a pandora's battery and memory stick from ebay