How to prepare surface to lay some tiles along step intio shower?

[fitzykev]

Can anyone tell me after i clear this out what can I refill it with and let set before I lay some tiles on top? Something very strong and fast setting as I want to have it finished for visitors arriving

 

[TeaAndBiscuits]

Just mix up an extra bit of tile adhesive (assuming you're using powder/cement based) and pad it out with that.