Refresher course on Tampons

Hello, I'm in my 20s and started getting my period when I was 11. I never liked Tampons so I've only ever worn them twice and that was many years ago. Tomorrow I have a plans that I can't cancel and they involve swimming. I started spotting about 3 days ago so I figured I would wear a tampon while I swim so I don't get my swimsuit messy. (Even though I've just been spotting). Can someone please explain to me how to use a tampon properly again. I would really appreciate it and please don't post any mean comments.