Creating equal opposite part

New and still learning. I created a part and I want to now created the other part that fits into this part. how do I go about doing something like that? I dont see how to attach pictures but lets say I have an “S” created. I now want to create the part that fits around the s. obviously that would be simple but using that as a scenerio. you have one part and need to create the oppposite contoured parts. How do I go about doing this?

Thank you

Hi Tyson,
I think the subtraction-feature is what you are looking for.
Have you consumed the tutorial-video series already?

Cheers Matt

Subtract would probably be what you need, as Matt suggested.
If you can post a picture of your scene here it will help us to come up with a best way of doing what you need.