1 - convert your private key into your public key and copy your public key onto something that will transfer your public key to an "online computer"

2 - use an online computer to view transactions of the public address/key and to be able to see the unspent inputs of the public key/address

3 - use one of a number of programs/services that can create an unsigned transaction for you

4 - copy the unsigned transaction from step 3 onto a device used in step 1 and copy it back to your offline computer

5 - use your offline computer to sign the transaction in step 4

6 - transfer the now-signed transaction back to your online computer and push it to the network