To add a variable,do this:
1.Onactivate - Player - addvariable - testing (amount in next box) 1
2.Onactivate - client - displayvariable - client - chatmessage - testing
Then,it shuold say in the chatbox:
testing is 1
Then if you keep clicking it,It will keep counting up.add a - to make it subtract one.
Client variables are variables you always keep,player variables are ones you lose when you die.Thats just simple variables,and I'm running out of time.Their's a tutorial about this someone,search it.