Problem Editting An Object

Hi all,
I am a beginner at Blender, and I’m having a small problem in blender and was wondering if anyone could help me.

I created an object and added it to a new group on one plane. Then I made a second object and added it to another new group on a second plane. So I moved the second object to the first plane with the first object.

The problem being, now I am enable to select and edit the first object.

Thanks, Knott.