a body of mass W is kept on arough surface angle of friction is theta what is minimum force required to just move it?

If u draw free body diagram, u will come to know that the sine component of weight and the force that you apply act down the plane(for min force reqd the force has to be down the plane) and the friction acts up the plane. Normal force perpendicular to surface touching the plane. So writing eqns,  F  +  mg sin a   =  f_s  where f_s is limiting friction. Rearrange and u'll get the answer.