Prepare the floor. Lay down roofing felt and staple it to the flooring with a heavy duty stapler. Place steel mesh over the felt and tack it into place with tack nails and a hammer. Cut out the mesh and roofing paper where it covers the drain hole to expose the drain hole with metal snippers and a razor. Mount the bottom flange of the drain in the drain hole using the drain bolts and a hand wrench.
Cover the shower floor with a 1 1/2-inch base of sand mix cement mixed to a grainy texture that is similar to wet beach sand. Pack this cement down so it is sloping towards the drain on all sides. Set your level across the floor to verify the slope is even on all sides. Let this dry fro 24 hours.
Place a shower liner over the dry cement installed in the above step. Smooth the liner out over the entire surface of the floor and up the sides of the shower walls. Nail the liner to the walls with a hammer and nails. Trim off any remaining material with a razor.
Create one more batch of sand mix cement, mixing it to a grainy consistency again. Spread the material across the liner. With the hand trowel, pack the sand mix cement into a solid, flat floor that matches the contour of the layer beneath your newly installed shower liner. Allow for 24 hours of drying time before walking on the flooring.