WPF Command approach.

So i have MVVM, or at least I'm trying to make one, where the Command is enabling the Button Click when all the Textbox fields are filled with some values. Thing is i can do that with one, but don't know how to do it with multiple parameters that need to be checked. I have seen some MultipleParam stuff with Converter but i don't understand the concept behind it so if there is some different approach here or someone to explain it how is that working. Thanks