I know this sounds really stupid, but I need to understand one thing about paper wallets. I understand that they are created offline for safety reasons, and that the private key never contacts the internet until the funds are to be used...but if it is completely offline, how is it that you can send bitcoins to wallet using the public key in the first place?

So I create this paper wallet offline, then I send a bitcoin to it from an exchange online. Okay so now this 1 bitcoin is sitting in an address that isn't even online? When I want to spend the bitcoins and upload them to an exchange, the wallet magically contains the bitcoins? I tried researching this but I still don't really get it. Sorry if it's really dumb, but I just started recently. Thanks for the help!