Step 1: Hooking up your PSP.
Step 2: Learning the Root Menu.
Note the folders, and go to the one named PSP. It should be the fifth folder. Double click, and open.
Step 3: Putting the applications on your psp.
What you want to do, is click and drag the application's folders to the GAME folder. If the application has one folder that contains another folder (in which the second folder has all the files), delete the first folder and keep the second. If you have a folder leading to a folder, your PSP will say it is a Corrupted File.
Step 4: Test and use!
-One folder leading to another
-An incomplete download/transfer. Reconnect, delete the file, and try again.
-Your PSP Is not compatible with the application. This means you either need to Update your Custom Firmware or the application just won't run on your psp model (Example: Some applications can't run on PSP Slim/Lite).
Enjoy your homebrew and have fun!