i would like to know : what is the first in turkish grammar to learn,,, i learned the first part.. merhaba , nasilsin, iyiyim... which could be the next part to learn in turkish grammar...thanks...tesekkur ederim

Start with the Basic Grammar chapter on this site, and Basic Turkish for vocabulary.

Start by getting an understanding of vowel harmony and the idea of suffixes......understand the possessive suffixes and the personal suffixes and you are a long way towards getting to grips with the Turkish language.

If you want help with vowel harmony then there is a practice tool that I wrote ages ago......feel free to make use of it:
Here