How to set a frame so that it automatically fills the width of a section.

Trying to walk through setting up something using Gemini but it ends up stuck on this ‘auto layout’ business.

I need to create a section in figma then nest a frame inside that section, in which to place content.

the section does not have this auto layout attribute.

does the frame within this section:

1. need to be sized to fit the width and height of the section?
2. need to have layout settings placed upon it in order to automatically fill the width of the parent section?
3. need padding set on it?

please do not simply link to other content.

any assistance specific to this question will be greatly appreciated.