Staff of Healing
 

I have looked all over and can not find where to add a staff of healing in HLO.

First, open the Weapons Tab and use the + Button to open the purchase panel.

Once there ensure you have the display options configured so you do not hide anything and simply type "Healing" into the search bar and you should find it quite swiftly.

You can also do so from the Magic Items table with the same guidelines Ryan outlined. Staves show up in both locations because they are both items and weapons.