About GNU Bignum library

[Taslim Arefin]

Hi,
I am actually looking about ways to calculate big integers in C language. Then I found GNU by google search. So I'm wondering that since it is a library,how can we use it in language in compilers like Turbo C.
Somewhere in a thread I found someone using this library(I may be wrong) by declaring a header file #include<gnu.h> or something like this.
Please clarify  how can we use this library in C language/any programming language if possible and what are the steps to do that or any sort of user manuals.
I'll be happy if you kindly clarify these things.

Regards
Arefin