Trying to get apple tv remote to work with imac

I have an imac in office room and apple tv in the bedroom. My imac can see the apple tv in airplay and I select it and I goto to the bedroom and I can see the image from the imac on the Apple tv. The problem is how do I control the imac using apple tv in the bedroom? I am trying to view the imovie or photos in the bedroom with apple tv remote does not work? How do I get this to work? I also like to mirror the process so that I can control my imac with the apple tv.

Thanks

James