"Can someone help me where can I get some ideas to develope my own wireless tx and rx ?"

OK so you dont want to buy something "readymade". While this approach is the best to learn, it sure is the longest also !!

Anyway you can check out the application notes on this site, besides in the links already given : http://www.radiometrix.co.uk/products/product1.htm

Before you venture out to build them on your own, going through the application notes will give a good insight as to where the technology stands currently.

There was a time when a MCU development kit had a 6 digit LED display and a hex keypad for user input !! And I have entered hundreds of 8085 mnemonics via this keypad - and believe me, the code finally did what I wanted it to do. Sure it had 8255, 8253, 8279 also on board.

Times have changed.

Have a nice weekend.

Raghu