1. what can I do now?
Get involved in extracurricular activities. Take on leadership roles.
2. How will I start my GMAT prep. from now?
Look on the forums here. The best option is to buy some books and just start reading.
3. if I have a good CGPA (like 3.9 or 3.8) and good GMAT score (like 700+) then, will I get any full free scholarship or scholarship in foreigh University like USA or others?
Probably not unless you have something else really impressive. Full ride scholarships are rare - and even so, a good gpa and strong GMAT won't be enough to get you a scholarship -- i know people with a 4.0 and 780 who got nothing at the GSB. It just depends on what else you bring to the table.
4. Which Books I can follow to have an excelent GMAT score?
The Official Guide 11th edition and
Manhattan GMAT books are good.
5. only GMAT and good CGPA is enough to ahve a scholarship for Graduate degree like MBA??
No.
6. What I have to do if I want to have a full free scholarship??
Honestly? You can't guarantee it. No matter what you do. Why not consider loans?
7. How much time i have to spend from now to have a score of 750+ in GMAT?
Depends on the person. For some, its two weeks. For others, its months. For some, a 750 is likely just not possible no matter how much they study.
Based on your english skills in this post, I think you have a lot of studying to do to break 700, much less 750. Offhand, I'd say the majority of people who score above 700 put in between 100 and 200 hours. A 750 would probably require at least 300 hours for someone like myself, maybe more.
You should be prepared for the reality that you might not be able to get a 750. Some people just can't break 700. I know one guy who took the GMAT four or five times (I forget) over the course of three years and never broke 600. (He ended up at UCLA after 2 re-applications).