A wallet is considered cold if it is kept offline without any internet connection. In order to broadcast transactions and keep up to date on your balances you also need a watch only wallet that is online, but does not have the private keys in order to sign a transaction. The watch only wallet creates the transaction, but cant sign it. You transfer it to the offline computer (e.g. via QR-code or USB-stick), sign it there and transfer it back for broadcasting.


#1 get additional computer
#2 install software
#3 dont go online