How do I go about buying paint?

So, I've been needing to paint my room, and I'm going to buy paint from walmart. I have social anxiety, though, so what is the information I provide to the person at the counter? I just get my swatch and tell them I need one can of paint and that's it? Will they ask me what kind of brand or finish I want? I have no idea cuz I've never bought paint before, sorry if this is a stupid question.

Don't they have a shelf of different paints or something? There aren't walmarts where I am so I don't know if it's different here but whenever I have bought paint I just walked in and went to the paint section and read the back of the different paint cans. Someone usually asks me if I want help but that's all. If you want a specific shade of colour I think you can get them to mix one for you or something but I've only ever just bought common colours.

Sorry if this hasn't been any help