I want to fit a remote control receiver to my ceiling fan.can you help and where to by it

Home depot, probably most large stores like that. Maybe Ebay?

Found this on Ebay:
Hampton Bay Ceiling Fan Wireless Remote 191-691 - eBay (item 280256576685 end time Aug-17-08 15:56:02 PDT)
Although it is out of stock, here's one from HD:
Hampton Bay Wireless Ceiling Fan Remote Control - T1&R1 at The Home Depot

Hampton Bay ones are unreliable. See if you can find a different brand. Try any place that sells ceiling fans.