Steam header files - how to access them?

Hey guys, I’m messing around with Steamworks right now and I already done it to implement steam into my game (overlay works, tested out the achievement blueprint nodes - they work perfectly for my game to.) - so it seems that Unreal can access all the steam functions. But I find no steam functions. For example, I wanted to code this:

  - SteamUtils()->SetOverlayNotificationPosition( ENotificationPosition eNotificationPosition )
Sets which corner of the screen you want notifications ('toasts') to appear. Default is the bottom-right corner of the screen.

But Visual Studio says that he cannot find that SteamUtils() and then even not the SetOverlayNotificationPosition function. How and where I have to include those steam headers? They have to be there because the blueprint nodes can access them, but me not… Any help? Thanks!