im wanting to know if its possible to add a wallet i have on a site that i signed up to to my Qt wallet and be able to send and receive from the wallet i got off the site i was using?
If the site is a hosted (shared) EWallet (e.g., Mt. Gox, Instawallet, bitZino, etc.) then no, you can only send a payment (or request a withdrawal, however they describe that feature) from that EWallet to an address from your own Bitcoin-Qt wallet.
If instead this site is a hybrid EWallet (e.g., Blockchain.info/wallet) then you can export the private keys from that service and import those keys into Bitcoin-Qt. It takes some command like skills but it is technically doable and fairly straightforward.
So to summarize, when you have funds with a hosted (shared) EWallet service you are ceding control over your coins to the operator of that service. You have and account there and can request a withdrawal but you have no direct access to the funds in the account. When you have funds in a local wallet (e.g., Bitcoin-Qt, Mutlibit, Electrum, Armory, etc.) or a hybrid wallet (Blockchain.info/wallet), or mobile app Bitcoin client (Blockchain for Android or iOS, Bitcoin Spinner, Bitcoin Wallet for Android) then you and you alone have control of the bitcoins.