How do I fix Roblox Model Joints & StarterCharacter Issues?

I'm trying to make a game with a custom StarterCharacter. The model for it is like a normal Roblox model, but with a custom head and two tails on the back. I screwed up the joint system, and can't figure out the right way to join the stuff together with the plugin Character Creator. Plus, when I put the model into StarterPlayer, and start the game, the model just falls down or either falls apart. Does anyone know how to fix this, or actually help me? I usually can't find the right answer on YouTube, and what I'm doing feels a little complex, but I'm not sure. If someone could help me, that would be good. But another thing is that I have a separate model that I want to put onto the character model, but when I group it with it, it gets a little cone thing around the circle shape that the object has. Look at the screenshots as shown below. So anyways, as I said, if anyone could help me with that stuff, then that would be good. Thanks, Ben.

IMAGE 1, BEFORE (https://ibb.co/W02ffNp) IMAGE 2, AFTER (https://ibb.co/34GPk9P) IMAGE 3, BEFORE 2 (https://ibb.co/98GNPPY) IMAGE 4, AFTER 2 (https://ibb.co/vz4WX1z) IMAGE 5 (https://ibb.co/fXMLpbk)