How to add banner position

Hello!

I am using T3 Bs3 Blank-Template and need to add a new block on top, hat holds two positions:

Position "leaderboard-standard" shall display a superbanner ad in "Large", "Medium" and "Small" screen.
Position "leaderboard-mobile" shall display a mobile-ad in "Extra Small" screen.

I have made a new block leaderboard.php in which both are placed:

[code type="xml"]