Using Cargo Bays?

[NASAengineer]

So I want to build a mothership made of the mk2 parts. I want to use the cargo bays to hold parts to create smaller ships which I could then send down to a planet's surface. But I can't seem to figure out the cargo bays. Parts stick where they shouldn't stick. They won't go on where I want. It makes no sense to me. Can someone give me a quick tutorial?

Thanks in advance!

[Wanderfound]

Hold down alt to disable radial attachment, don't let payload parts clip into the walls, strut inline-mounted payloads for stability, use docking ports or decouplers on cubic octagonal struts to mount payload radially. See the illustrated tutorial in the third post of the Kerbodyne​ thread linked below.

[NASAengineer]

thanks wanderfound!!