OnActivate>Self>spawnProjectile>(which one you want here)>[ ] [ ] [ ]
This is how to make it shoot when you click it, now some times it doesn't shoot at all, if it does go and add something likea five in the first or last bracket after the projectile. There is also a way to make it keep shooting which is,
OnActivate>Self>FireRelay
OnRelay>Self>SpawnProjectile>(which one you want here) [ ] [ ] [ ]
OnRelay>Self>FireRelay.
Now a word of caution, many servers will get mad if you use the second one, especially when the projectile you choose is a rocket. Now it won't do any dammage unless it's in a minigame but people still don't like it abused.