Remove the Lenovo:
I assume the Lenovo appears in the Shared section of the Finder Sidebar, click the eject button. If you had dragged the share into your Login Items, remove it with the - button in Users & Groups Preferences.
Add the Asus:
With Finder in the foreground, click Go > Connect to Server (or CMD+K) and enter the IP address (smb://[ip.address]/) and login info for the Asus. If you know the hostname of her Asus, use that instead of IP address so that if the address changes, you can still mount it.
Or, if the Asus appears in Shared > All (basically a local subnet discovery like "Network Neighborhood" in Windows), click on it and provide login credentials. Make sure you check the box to remember the password.
If you want to mount it whenever you login, drag the share into your Login Items in Users & Groups Preferences.