How do I install this certain video card with my HP Pavilion a250y?

The computer I'm currently using is the HP Pavilion a250y and it runs Windows XP. The video card that I'd like to install is an Nvidia GeForce 6600GT 128 MB DDR3 Dual DVI TV. I've checked the specs for my computer and it supports AGP video cards but I'm not quite sure if that's the type of video card that I have. Help a mildly tech-savvy gal out to install this please? Thanks in advance.|||I'm pretty sure that it is a AGP card but to be sure you can just check online or see if the edge matches up to the slot. detailed instructions to intall video cards can be found in the box that comes with the card or in the computers manual under installing expansion cards.