Drop down menu dependent on another drop down menu

I am trying to create a form for clients to submit, however I would like them to select the region relevant to them from a drop down menu and then another drop down menu will populate based off those results.

For example, the first drop down menu would have: Region 1, Region 2, Region 3, etc. And then if they select Region 1, the dependent drop down menu will include Result 1, Result 2, Result 3 and so on. This will need to happen for each region.

I have had a look around here for similar solutions, but I think I have confused myself more than anything as I am still fairly new to writing scripts. If anyone is able to help me out that would be wonderful.