Need help. my layer mask is not working!

My Issue: working with a new image pasted from clipboard (so background was white).  I would apply a mask layer and start painting with black...I would get a brush-sized dot but the rest of my brushed mask looked like it was doing nothing. In my Layers panel, my whole mask appeared, just not the image.

My Solution: unlock "Background" layer.

Inserted image below is BEFORE unlocking. You can see the dot (lower left under log) as compared to my Layers mask thumb. Simply unlocking displayed my working mask instantly (no screen shot of that).

horungaaar

Having looked at your screen shot - if you want to mask the stroke (Layer 2), you will need to add a mask to Layer 2. The mask on the papper layer only affects the art on that layer.
Another option would be to group the two layers, and then add a mask to the group.

Another thing to check: Do you have an active selection perhaps? That selection could be hidden if you pressed Cmd-H, so make sure that is not the case (look at the 'View - Extras' menu. Make sure it has a checkmark). If there is an active selection, then all tools only work inside that selection.

It's a bit difficult to see, but you have another layer on top of the layer with the mask. That other layer won't be masked, so its content will remain visible no matter what you paint in the mask below.

I watched 15 minutes of the vid, which was itself very poorly produced as far as teaching. At any rate the term "vector" never ocurred. Just guessing an interpretation of what you may mean in your difficult (for me) to interpret post: you have a selection or mask, therefore you can only make changes within the selection, or any changes you are making are masked. Either event is normal. Good luck, keep at it, don't give up.

What are you brushing on? You can not brush on a Vector Layer mask.  You need to user vector tools on vector mask.

Can you post some screen shots of what you are trying from your computer? Watching the tutorial that you are trying to follow will not show us what you are doing that isn't working.