We would always recommend using a suitable waterproof sealant to seal your shower.

Ensure that the shower is completely dry before you proceed.

1: Apply a bead of sealant either side of the central tower vertically.

2: Horizontally between the tray/base and the back panels (AVOID the little water gullies that allow water to return to the tub)

3: Around the top, between the back panels and the ceiling.

You may wish to seal along the front, where the frame joins the tub/base and also the ceiling, but this is optional.