Zain Mughal :
but i have a card now.... how i fit into my pc :/
I'm sorry, but you'll probably have to buy or build a new PC. There's no other way of using the card properly. You can get some cheap parts though; the 550ti is not that powerful a card, and therefore not easily bottlenecked.
Edit: Oh, and next time, do some research before you buy any parts, and this forum is great if you need any more help.