Time Capsule - create extended network, How?

[sparkiUK]

I really can't get this to work. I have a cable modem with a netgear wireless router connected to it which works fine and i can access it wirelessly. Except from the bottom of my house where the signal won't reach. What i want to do and can't seem to get the correct settings, is connect my Time Machine wirelessly to the Netgear from say halfway down the house, and then from my bottom floor for example connect to the internet via the time machine, if that makes any sense. So the time machine basically picks up the signal from upstair and broadcasts it out so that i can pick it up further away.

Can someone please explain the settings i need cause no matter what combination of options i choose i can't get it to work and it's driving me nuts.

thanks