I am 26 years old , I live outside of the united states ........but here is the deal...I have a green card ( permanent one ) , I have finished 4-year college     ( PE) in my country with really good grades and good GPA( around  4 ) , I have never broken any kind ow law , in perfect health , never had any kind of surgery except for tonsils in the age of 6 , I have 20/20 vision....

I will be around 27 and 3/4 when I move to usa on permanent basis ,  so....

1.) what is my next step after that in order to become fighter pilot ( it doesnt really mater in which branch , as long  it is flying fighter planes )...and...

2.) what can I do in the meanwhile in my country in order to prepare myself better for that great , great achievment

thank you very much for your answers , truely

Your biggest issue will be citizenship.  You must be a US citizen at the time of commissioning.  Unfortunately, to become a pilot in the USAF you must be selected before the age of 30.  Unless there is a way to become a citizen and earn you comission before you turn 30, I doubt you will be able to fly for the USAF.

So , if I would be able to somehow resolve the citizhenship issue , I would be in much better situation , I presume , right ?

Yes, if you get citizenship and are able to complete Officer Training School before your 30th birthday, you could get a pilot slot (precluding factors I don't know about).

and how many flight hours should I take , also , what is the average cost of a flight hour
should I get my PPL , will it increase my chances

Yes, getting a PPL would help.  (That's not your biggest concern now.)