I checked out the website and read about the enrollment. My diploma is from my country High school diploma, I just noticed in the necessary documents in the website that I need “validation or validation request of your academic qualifications” for non European. what does that mean? what academic documents do I need for this school ?

abed,
the validation of your secondary education is also necessary if you want to go to university in spain. you can apply for the validation in madrid when you arrive. you fill in the form

http://www.educacion.es/mecd/titulos/files/Anexo8nuevo.rtf
http://www.educacion.es/mecd/titulos/files/Volante.rtf

and you go to the ministry of education and you attach the documents, they will send you a letter in 3 to six months that your high school diploma is validated and they will return the original documents and will keep a photocopy, and they will give you a certificate that your tawjihi is equivalent to the bachillerato.
with the “volante” you can enrol while you are waiting for the validation.

you will need your
high school diploma tawjihi
high school transcript
basic education diploma
basic education transcript
get official copies and have them legalized (go to spanish embassy and ask what they require to legalize and translate these documents)
you keep originals.

you have little time left.