Hi I just found this site last night its really imformative

My 11 month old cat Sammy is Pregnant and has a couple of weeks left I think, Does anyone have any tips about what I need to do when she starts giving birth I was told that cats usually dont need any help even. I have made up a birthing box for her. I was also wondering about about weaning I think you need to do it from 3 weeks but I dont have a clue how to do it as I do I need to get another litter tray? I have never had a pregnant cat before so dont really have a clue any help would be appreciated.
Thanks
Richard