Text Field Properties

Hello 

I would like to understand how to add rules in a new document.

For example, in a box which must contain a UK sort code 12-34-56, how can I set it up to let the people insert their sort code and have automatically the "dash"? Else, the UK postcode (letters + numbers) ?

I am not confident at all with java scripts and I was looking for a website to understand the basic formulas.

Thanks in advance