Time Machine: TC earlier and now external HDD

Hi there!

In my Mac Book Pro (10.6.8) the time machine (TM) was 1.5 years ago configuered to make back ups with Time Capsule (TC). However, now I do not have/use the TC anylonger. How can I configure Time Machine (TM) to make back ups with an external hard drive (USB, 1TB)? When I click on "choose back up volume" on TM the one and only option left is to "configure time capsule" - which does not exist anylonger. It only recognises the non-existent TC and not the USB external HD. When "configuring TC" it searches for wireless airport, which I also do not have, as I'm sharing/using my neighbour's internet connection. How can I make the TM to recognise the external HD?

Thanks a lot for your help!!

Ruveni