Maysarr,
With all due respect, I doubt that it is in any way possible to explain to you - within the scope of this forum - how to develop a UMAT subroutine, unless of course you have a pre-written UMAT that you just need to add in. And even in this case, the best - and probably only - place to look for reference, including how to merge in the UMAT, is the ABAQUS reference manual.
Best of luck,
-- drej --