Couple of ways to do this.

1. Use the wowhead icon to create ["ITEM"]["/ITEM"] and type the name of the item. without all the quotes of course.

example [Earthshaper] ["ITEM"]Earthshaper["/ITEM"]

2. Same as above but use the item ID.

example [Earthshaper] ["ITEM"]45521["/ITEM"]

3. Just provide the link to that item.

example [Earthshaper] hxxp://www.wowhead.com/?item=45521