Opening a gap for insertion into a track

I’m a new user and can not believe I have missed how to perform this simple function. I have 3 seconds of silence in the middle of a track. I want to extend this to 6 seconds (exact times not required). How do I “open a gap” in the track to insert the silence? The time shifting tool seems not to to allow the stuff to the right of the cursor to be shifted further right, which would be the obvious approach.

Click anywhere in the 3 seconds of existing silence then use Generate > Silence to add in the extra 3 seconds. You do not need to “open up a gap”. Audacity will insert the silence into the selected track where-ever the cursor line is currently positioned.

The Time Shift tool treats the track as one piece, moving the entire track left or right. If you want to move the right-hand portion of the track, while leaving the left-hand portion where it is, you need to Split the track: place the cursor where you want to split it and hit Ctrl+I. You should see a vertical line appear at your cursor indicating the split - now, each part of the track can be moved independently.