Creating a table with a list of ids or objects

This is another basic question, I've been trying to find the answer to for days. I only come here with these types of questions, when I'm researching through the same resources over and over and cannot find a solution.

If I want for instance a cart, so it has multiple items or item ids (ints) within the one instance.

Do I just keep adding item after item using the same id?

I am confused and just can't get my head around it. I am sure there's information out there, but I have failed to dig it up.

Is there a simple way to explain the concept of how this is done?

I happen to be creating a project in VS using Sql Server, but really the principles remain the same, I'm guessing.

Any help is appreciated.

via Chebli Mohamed