Here an example:
OnActivate Self FireRelay
OnRelay Self Firerelay
OnRelay Self VCE_Retrocheck LastMsg = "Fire"
OnVariableTrue Player SpawnProjectile 1000 Tank Shell
its something like that
when you say Fire, it will shoot to the direction you are looking at.
instead VCE_Retrocheck, you can use VCE_IfValue for little more advanced things like <var:player:firing> but i dont really remember , just use ingame VCE manual
instead spawnprojectile you can do things like add velocity for super jump , do value for player jump etc