EOS 400 help

A mate of mine has let me have use of the aformentioned camera for a week or two, but has mis-laid the handbook.

It years since I've used an SLR and the first digital SLR I've used and am having a few problems using it in manual mode. Can anyone tell me how to adjust the f/stop manually? My efforts have led to be being able to adjust either the shutter speed or the f/stop but not both under the same mode.

Hope that makes sense

Lance