Hi,
Designing your own transmitter for the 2.4GHZ band will be very difficult. You need to have experience in those frequency and have the required lab material for tuning it.
The best way is to find some module or kits over the net. Try google.
Here are some links to such material or amateur tv transmitters :
h**p://rf-links.com/24_transmitters.htm
h**p://www.ramseyelectronics.com/cgi-bin/commerce.exe?preadd=action&key=C2001
h**p://www.qsl.net/n9zia/atv/
h**p://www.13cm.co.uk/html/13cm_atv_transmitter.html
* = t