If you're new to the whole system, why do you need .5BTC ASAP?
I could work something out if you want, but to ensure protection on my end you'd have to send funds via Paypal first.
Your payment would be protected by Paypal, although if I send first I'd have no protection, so hopefully you understand.
You may also use an Escrow service or other methods to purchase BTC.
Buying through paypal is still dangerous even through escrow.