[Help filing in shapes created with pen tool]

Apologies, I'm sure this topic has been covered a lot but I'm asking here as I don't know the best way to articulate my query so struggled with searches.

 

I'm creating a drawing using the pen tool. I want to fill in different sections of it to create a stain-glass window style. How do I go about creating the different shapes I want to fill out of the lines drawn? Once I've done this will I be able to delete the lines without gaps between each shape created from filling? Apologies again, I hope that this makes sense!

Image attached. I also want to remove some sections that overlap.

[Adding/Combining Curves and Pen Lines]

I'm trying out some basic shape stuff in Designer for Windows and I'm unable to Add a straight Pen line and a rectangle together (I'm trying to create a drip effect). However whenever I select both the rectangle and the line and try to Add them together the line disappears. Same thing happens when I attempt to combine them as well. I've tried shifting the layer order around and still nothing. I've attached an image to show where I am at the moment and what I'm trying to achieve. Any assistance would be greatly appreciated!