I'm trying to make one function go right after another function finishes. For example, say I have an EaseTo function (which would make an MC ease to a certain coordinate), and i want an MC to move to the coordinates 0,0 and once it's arrived there, to move to 40,100.

What is the function for this? I've seen a doNext command once, is this what I'm searching for? If so, how do I use this command?

You could also use callbak mechanism.
Whenever a function ends up it notifies its state and then you can go on
to call other functions e.g.

function f1 () {
// do your stuff
onFunctionOver()
}

function onFunctionOver() {
...
}