Dear Ahmed Abass:

Usually, you need to imput the crystal structure, then imput your experimental data, after that you can select which parameters can change during refinement, e.g lattic constants, atom positions. The soft ware will help to compare the calcualted and experimental XRD patterns. If the Rp, Rw are low then 10%, then the refinement is successful. If not change other parameters like FWHM to continue the refinement.