I thought the default had some skills ready for you. If there's really nothing then you can always make one.
Increase the array size, change the skill option to healing(HP of one ally or so...) and figure out how much the SP cost and the healing points.
To use the skill, make sure you added the skill on character's classes. You can use the skill in menu or in battle. Or use an event and choose a complete healing instead (If you want to make some kind of Inn event).
To make a shop, make a new event. Double click at the event layer should do it. Choose the shop menu, find it by yourself, it's easy. Add the things you wish to sell.