When the time comes and you want to send Bitcoins from your paper wallet you’ll need to import the private key or seed into a software wallet. While each wallet is different in its process the general idea remains the same:
Download a software wallet
Click on “New Wallet”
Import and existing seed / private key
Scan the QR for the private key of your paper wallet (this is much easier than typing the whole key)
Important! Do not do this process on a wallet that is already holding funds as it may override the current private key. It’s best to download a new wallet / app and import for this process.