Psp iso game

i downloaded a game psp and this shit came up when i opened the file:

[You must be registered and logged in to see this link.]

then i looked at the comments and it vaguely said to unrar it or something to make it a iso file, i have poweriso so i tried making a iso file and it said that it can only be done for 300 mb or you have to register (pay $40)

How do i put that game on my psp, how do i play it?

please help

Use 7-zip it's free,I had to use it a few times myself,because some iso's were rarred the same way