Click on 'Accounts' on the left side of the page. This will bring up a page that shows the name and From: address that will be used.
Scroll town until you see:
Primary Account Settings -> Name and Email shown as "From" address
Change the Name and/or email address to what you want to see. If you wish to use hers.com as the From: domain instead of his.com , enter that there too.
Click on the Save icon near the top left part of the page.