Question: I am teaching myself the very basics of design using [Affinity Designer](https://affinity.serif.com/) - and I haven't been able to figure out how to create a single shape from multiple vectors. 

For instance, if I am creating a basic outline of a car and need to start and stop lines - when I use the `join lines tool` it doesn't join two unrelated lines together - rather it completes the "circle" (path) of one line only. 

If I use the `join shapes tool` it completes all the unconnected lines, and fills in those spaces too - so I lose the shape I am after. 

AD's help index is not very helpful to someone with my near non-existent skills - so I'd be thrilled if someone on this forum can help.

Answer: 
I think what you are looking for is the compound. E.g. I was trying to create an object out of 2 shapes where the inner shape forms a hole. So I used the complement compound (The square with the circle and the intersection is missing).

For other stuff you might need the other operations for forming compounds.
Just to clarify a bit, I think you mean this: Say you had a line with 3 nodes, a,b, and c, with a and c being the endpoint of the nodes. You wish to attach another another line with two nodes d and e. You wish to connect the nodes b and e.

As of right now, I can't seem to find functionality of the program where it attaches two unrelated lines that AREN'T endpoints of each line.

I think the Pen module Affinity designed assumes you are always wanting to produce an endpoint to endpoint shape. But unfortunately, when creating lambda shapes, asterisks, x's, f's, $'s, etc. you're going to run into some issues. I would love to see the ability of the pen to create complex shapes that are much less dependent on endpoint snapping.