Conventional Missile Batteries and Land Based Cruise Batteries (Little Upsilon)

How do i use these, i read that it stays in the base but how do i select it when attacking a target

If you are within range. Select a target. Then, goto land based weapons. Choose the amount of missiles batteries. Attack either target or defenses. Its easy.

make sure you wipe out their air force, otherwise, they'll destroy not just the missiles, but the launchers too