Spam the drop button(which ever key u set for that) when planes near the ship...

Might need a while to get the hang of it.

This botton . to release your GOODIES if you have everything on default.

L and , are for raising and lowering altitude. By default, the . key is for dropping bombs.

Just to cover all the possibilities, check you actually loaded bombs. I used to forget every time I bought a new CV that bombers needed ammo loaded in the dock.

to drop your bomb, press . (dot) button 

left click to lock right click let go off bomb or check if u even have bombs loaded