The fifth step in solving a Rubik's Cube is get in the corner pieces on top. The algorithm to perform put in the corner pieces is R, T, Ri, T, R, T180, Ri.
When you have no corner pieces you want to have the corner piece in the upper right corner of the left face and then you perform the algorithm. When you have one corner piece you have it in the bottom left of the top face and perform the algorithm. When you have one corner piece have the rest of the corner pieces in the bottom left of the top face.
Only one more step after this one.