Here are the steps:
1) Offline: make a new wallet with seed and everything.
2) Offline: copy the master public key
3) Online: make a watch-only wallet using this master public key
I think you have already done steps 1-3
4) Online: go to send tab, fill in the boxes, click "preview" and copy the unsigned tx
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FQj0Jljo.jpg&t=663&c=_4sDStXGQJpYZg)
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FnEfA3AH.jpg&t=663&c=ZcQs7nXMnCFwVA)
5) Offline: transfer the tx from last step to your offline wallet, import it and click "Sign"
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2F1xOLKlm.jpg&t=663&c=0r_jatCI6I0TaQ)
6) Online: transfer the signed tx from last step to your online wallet, import it and click "Broadcast"