Short guide

1. Variables: It's something storing numbers or text.
2. default variables: are found in /playervariablelist. In this command is a description of all the default variables you can use without creating your own.
3. Using variables: in pickups like addmsgpickup, addannpickup and message type pickups. You can type /addmsgpickup $player_name$ is your name and it will display the name of the user using the variables. Check /playervariablelist for other variables.
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(MEDIUM)
4. Checking variables: You can use /changepickupcondition to check variables. /changepickupcondition player_name == VK.Angel.OfDeath will make it so only people with my name can enter the pickup. This is not very useful but you can create lots of things with other variables (like /playervariablelist). What does == mean? Read /conditionlist. There are 6 different conditions.
That's the basic the next part is the custom variables. Your own variables basically
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(ADVANCED)
5. There are two types of variables you can create. Player Variables and Property variables. Property variables will give the same value for everyone, while player variables have different values for different players.

You define them using: /addvariablepickup var_test 5. This will store the value 5 inside the variable var_test. var_test here is a property variable. That you can then use in /addmsgpickup and /changepickupcondition.

For player variables /addplayervariablepickup.

Two other commands are /addchangevariablepickup and /addchangeplayervariablepickup that increases/decreases a number by the variable/number you put into it
To someone who don't program 5 I will not be able to explain at all. I can do my best but I won't be able to make you get it. 4 can be explained but uses two programming concepts like == and AND. I think what the event staff is after is a short guide in a few sentences to explain everything. For 1-3 that's possible. But for the rest it's not
I believe everyone should be able to understand 1-3
But the rest is up to you guys.