Happy, on your clipboard map, find the CV you want to move to. You can double click on the icon to move you there. Once there, you should be looking out over the deck of the carrier. This is the "tower" on the CV. If all you see is water, and a few ships sailing nearby, that carrier has been sunk.
Look down at the bottom of the clipboard, and you will see some words. Tower, Hangar, Setup, etc. Click on "Hangar". This will take you to the selection screen where you can choose your plane, vehicle, or Guns. Select "Gun Ship or Field" with your mouse, and then hit ESC to lower your clipboard out of the way. On a CV, you will see a representation of every ship in the group, along with mannable guns. On the cruiser, you will have 8" and 5" guns available. The Carrier will have dual 5" mounts, single 5" mounts, and 40mm AA. The smaller screening ships will have 20mm available. If the circle representing a gun is white, it is available. If it is blue, it is occupied. If it is red, it has been destroyed. Click on the gun position you would like to occupy. Then hit ESC to bring your clipboard back up, and hit the "H" button to go to your gun and begin shooting.