I am first year PhD student.My fears are I have a lot to do on programming which I do not have a good background.I am ready to work hard but I do not know how far I can go.Can anyone give me any advice if u had such experience.

My advice as a programmer is learn Java or Python. They are relatively easy languages to program in.

I'm in a similar position. I will be starting my PhD soon and there will, at some stage, be some programming. Although i did programming modules in my undergrad i have never used it for anything and that was years ago. I suggest that you are completely honest about it with your supervisor, there may also be a course in the grad school you can do.
I told my supervisor about my situation when we first met to discuss the PhD. He was really nice about it- he said we can learn together. I think we may also be using Python. In my undergrad we were using Fortran.

Thank you guys.Your advices mean a lot to me and I will update you with my progress.