On topic :Uhoh.
Sounds like you have a slimline/spacesaver pc from one of the bigbox companies (dell/hp/gateway). This is what I had, and it was damn near impossible to upgrade, because space is an issue. Almost any good video card will need at least a 400w power-supply, and the slimline style case often makes do with less than 300w, and they don't make more powerful ones for those cases.
If that's NOT an issue, and you have a full size tower , than this is what I would do.
Step 1) Make sure your motherboard has pci slots for your videocards. Disconnect the power, unscrew a case panel, and see if your mother board (what everything inside the case is attached to, big flattish board) has empty slots on it.
If it does, then we can move on. If it doesn't you may have to grab a new one, which will take a whole 'nother topic.
Step 2 ) Check the writing on your power-supply. It should have a rating in Watts (like 400w, etc). If you are above 400w, that leaves you some options for your videocard.
If not, google your PC model, and google "Power supply upgrade for (model)."
Step 3) Look for a video card that fits your processor type (Intel). When you go on to Newegg/Tiger Direct/other, it will have options you can tick to narrow the selection. Look for : Power consumption , what kind of motherboard/processor, etc. Read the reviews that people leave, and ask here before buying, we'll help you out.