How to change icon:
Icons need to be named in capital letters. For example "ICON0.PNG", not "icono.png". Then simply replace the old one with the new one and your good to go. Place in main directory along with PARAM.SFO
How to change background:
Backgrounds need to be named in capital letters as well. For example "PIC1.PNG", not "pic1.png". Replace the old one with the new one and your good to go. Not sure the filesize requirement of these.
How to add Sounds
Ok, sounds have to be ATRAC3 format and need to be named SND0.AT3.
Heres a good tut i found on converting sounds to ATRAC (tut by iloveme888 :
1'st: Download GoldWave.rar - Install it. (GoldWave - You must login or register to view this content. )
2'nd: Download AT3_codec.rar - Extract it. (ATRAC Codec - You must login or register to view this content. )
3'rd: Right click on the atrac3.inf file and select Install - You may encounter a prompt saying: "The software you are installing for this hardware has not passed Windows Logo testing" click on the "Continue Anyway" button.
4'th: Open your mp3 with goldwave. Under "save as type" choose WAVE. Under the attributes option choose ATRAC3.