can be done youself pretty easily
you just have to unscrew the side of your case, and remove it
as you currently have an intergrated card you shouldn't have anything in the AGP slot, it'll be the brown one on its own at the top slightly separated from the white slots
just slot your card in there and screw it in, you'll also have to plug a small power connector in, it'll be like the connector that goes into the back of the floppy drive.
then plug your monitor into this card connector instead of the one its currently plugged into
if nothing comes up when you boot then swap the lead back to your old connetcor and go into the bios (F2 or 'delete' during the system test)
go to the advanced section and change the 'graphics adator priority'