Your shoulder is made up of about eight individual muscles but the biggest and most important are the deltoids.
This is a large triangle shaped muscle with three muscle heads.
The front deltoids, the side deltoids and the rear deltoids.
Their function is to raise the arms and assist the pectoral muscles.
That means basically all chest exercises will also work your delts.
That being said the best overall exercise for the shoulders is the overhead press.
It works all three muscle heads of the deltoid and should be included in any workout.
Other variations or exercises with similar movements include handstand push ups, high incline bench pressing and push press.
If you want to isolate your shoulders.
You can also add the following to your routine:
front raises, side lateral raises, rear lateral raises, upright rows and face pulls.