Ok, I did it, the instructions:
You must download the file SDL-1.2.12-1.src.rpm from the link that u gave me
http://libsdl.org/download-1.2.phpThis is a .rpm file, u have to convert in a .deb
Install alien:
$ sudo apt-get install alien
then u have to convert the file:
$ sudo alien SDL-1.2.12-1.src.rpm (use the correct adress, example: /home/username/SDL-1.2.12-1.src.rpm like this:
$ sudo alien /home/username/SDL-1.2.12-1.src.rpm)
The file will be stored in the your user name with the name: sdl_1.2.12-2_i386.deb, then double click and enjoy!!!!!!!!!!!!!!