send to online wallet ie spend bitcoin from cold paper wallet ,without losing the remainder All the answers I see here are just confusing me. What is a ' client '? Is it me, my computer, my online wallet, the person selling to me or buying my bit coin or what ? I just want to know how to send bitcoin from paper wallet to online, to spend, and what to do to avoid losing the change remaining  in   the paper wallet. I GUESS it is like this...empty the paper wallet to an online wallet. Pay the other party by sending off bitcoin. Then make a new online wallet - must I  ? Put the remainder bitcoin  in there Make a new paper wallet.Send remaining coin back to new paper wallet. Sounds simple? But I have NO IDEA about how to use the private and public keys. Do I have to make a new private key for every step in the above ?
Client normally means the wallet 

You don't need to give money to someone to make you a wallet. There are many free wallets like electrum , greenwallet, coinomi which create a address for you and also make you the owner of your private keys

You also don't need to send the money from your paper wallet . If you are able to destroy you paper wallet safely , you can sweep the bitcoin from your paper wallet to coinomi wallet .

No need to make a new private key every time .