How to combine paths into a shape that I can fill in with colour?

Hello. I'm trying to do a very simple illustration of a jam jar. I've used paths to illustrate the various elements of the jar, but have run into two problems. The first is that I don't know how to colour the bottom of the jam (1) - it doesn't seem to recognise that white space as a space to fill in, which I guess is because it's made up of different paths not necessarily connected to each other (but that I don't know how to connect all of them).

The second problem (2) is that the the glass of the jar is overlapping its lid, and I can't seem to be able to get rid of the line that is at the top of the jar. The jar is actually a rectangle very slightly curved at the top and the bottom.

Image is attached. Any help is much appreciated - very new to Illustrator (as you can tell) so many thanks in advance!