rune = text?

[Thoric]

how do you make a trigger so when a person moves his unit over a rune, a description or hint or something like that appears?

 

[Renendaru]

Well you can't detect it being scrolled over, but you can detect it being clicked. After that show the floating text to the player.

Edit: Misread your post.

 

[Exide]

Create a new Dummy unit. Give it the Rune -model.
Place it on the map, where you want it.
Add a trigger: 'Unit - A unit comes within range of *Unit*' (Where *Unit* is your "Rune Unit".)
Then add your actions. Possibly floating text.

 

[XeNiM666]

You can create a region on the rune and when a unit enters the said region, check what conditions you want, then display the message.