you are missing the readme (updated each patch in the game directory)

Excerpt:
*** Gameplay additions & changes ***
1- Ships can now bombards. In order to do so your fleet must have:
a) big guns (range 5 or better)
b) be in offensive posture and at sea
c) must not have bombarded this turn
d) have the order "bombard" activated.
e) Have enough ammos.
A valid target are units in structures (coastal province with harbor)
if you have an army in the region, or are landing in the same turn.Beware, the enemy can strike back...