project smaller image into a bigger one

[rich2005]

Going for the cropping method. You are almost there, this is the frame from your video where you apply the crop. That was ok, but nothing to crop.

   

You are on the wrong layer  'für klein und groß'
You need to be on the 'Visible' layer.

Gimp has various indicators showing boundaries etc. Look for a yellow dotted layer boundary.