How do you parent a bone to another bone for a model?

I’m currently working on trying to solve an issue in the character model tutorial I’ve been working on, and I don’t seem to know what to do. When I try moving the feet of the model, the small bones that allow for the movement of it detach from the bigger ones, and the same happens with the pelvis bone. What do I do?

Here’s where I am in the tutorial video where I ran into that problem…

I ran in a lot of this problems when I started rigging my own characters. Especially when u actually have to generate the rig. I think CG Dive made a cool guide about all the essentials of rigging and why u happen to be in this situation.

(there’s an entire series about it, u wanna check the one you think is best for your case)

The shortcuts are [Cntrl+P] to parent two bones and [Alt+P] to disconnect them or clear the parenting but if I understood your problem correctly u have to go back to edit mode or to change something about the IK.