section

You really must give more details. The basic idea is to draw a cut line where you want to see the section and then project a view from that line just as you would a side view. But, it would help if you tell us the following:

1. Are you working on a board or in a CAD program? If so, which program?

2. What is your level of experience?

3. What sort of objects are you drafting?

4. Do you want all kinds of sections, broken-out sections, revolved sections, etc? In other words, what are you trying to show?

5. What is the purpose of having section views in your industry? That is, how do people use them?

Is it not basics of DOP ?

Cut the component by a plane along the section line.

Imagine how it looks

hatch the areas where material is there

Do not hatch the edges visible but surfaces not cut by the plane.

There may be many methods of doing it, but personally I do it by rotating temporarily a view (plan or elevation) above but on one side of other and extending the edges of each (plan&elevations) to intersect.

This give the section views (that is when i don't get it done by 3D models)