I created some calculations. How to add this calculations from Calculations tab:
to Cube Structure:
in Analysis Services.
You can't add calculations to the cube structure tab, and you're not supposed to.
The calculations in the calculations tab are in the cube, and can be browsed by end users.
They don't show up in the cube structure tab for the same reason dimension usage doesn't show up in the cube structure tab. That's not what that tab is for. That's just the way Microsoft designed BIDS to work.