To send off a request, you'll need 2 envelopes.
ONe should have the address of the celebrity on it, in your case David's Beckhams care of the agency/club. The other envelope should have
your address on it, and is the self-addressed stamped envelope.
Depending on where you live you will either need an international reply coupon (IRC) or a normal stamp.
The normal stamp can be used if you live in the same country as where you are sending the request (for David Beckham' agency that will be the UK, for his club that will be Spain). Then just stick the stamp onto the self-addressed stamped envelope.
If you don't live in the same country and are writing abroard, then you'll need to enclose a couple of IRC's which you can buy at the post office. They go inside the main envelope.
Then, just fold the letter and the self-addressed stamped envelope (and a photo if you want that signed in particular) and put it all in themain envelope with the celebrities address on the outside.
This picture explains it pretty well. Like I said, if you live in the same country then ignore the IRC bit and just put a stamp on the envelope with your address.
