Undecided questions
how is the alphabet of Arabic if we spell it in Roman letters? a,b,t,th,j,h,kh,d,dh...... or this is wrong?

Actually, you can use this link to hear the sound of the Arabic letter and how to write it in Latin litters, its really helpful:
http://www.youtube.com/watch?v=qFIJO5KSLLg

Dear Ablat,
I don't agree on this way in studying any language Particularily Arabic because: first, it is not a precise way because every language has its own sounds that cann't be transliterated into another. Second, transliteration will weaken your ability of spelling words, so you will not be able to write them correctly. The right way to learn a language is to listen, speak, read and write as per the original Alphabet and Phonetics of the language you are going to learn.
Best Regards,
Youssef