Hi:
You would need to provide the full model number or product number of your PC for anyone to be able to help you.
Use this guide to find that information...please do not post the serial number.
HP Desktop PCs - How Do I Find My Model Number or Product Number? | HP® Customer Support
There are a several factors for choosing a graphics card...
How much do you want to spend?
Will the graphics card work with the power supply your PC comes with?
Will the card fit in your PC's case?