How to add a path to LDFLAGS

I'm trying to set up a library called PBC (Pairing-based cryptography). And this library requires another library called GMP -(GNU Multiple-Precision Library).

My problem is after installing GMP correctly, PBC gives an error of:

gmp library not found add its path to LDFLAGS

I have no idea what LDFLAGS is and how to add it to the path.

PS: I'm using MinGW.