I have gone on the internet and learned about tss and how to insert it so now I just need the tampons. but I just don’t know how to ask my mom.
You have two options. The first option is that you can buy your own tampons. You'll want tampons with a rounded head for easier insertion, and if you're new to tampons ones that are mini or junior sized might be the easiest at first.
Your second option is obviously to talk to your mom, which it what it sounds like you want to do - you just aren't sure how to do it.
While it might feel painfully embarassing, your mother once had to ask her mother these questions. If you find yourself alone with her and you're both in a good mood, just ask, 'Mom, can I talk to you about something?' Moms generally want to be helpful to their daughters and feel thrilled to be included in their lives, so this should be a good opener.
Then say exactly what you've told me - you're interested in trying tampoms, you've done research online, etc. If your mother doesn't use tampons or feels shocked her 'baby' would want to use them, it might take a little time for her to get used to the idea. That's where saying you've researched them can help, as it shows you're making a mature choice.
Chances are your mom will be only too glad to offer advice and support.
However you get yout tampons, it might take more than a few tries to figure out how to insert them properly. While it can be frustrating, it's like riding a bicycle - once you get the hang of it, you won't forget. And remember, if you don't like tampons after trying them, you can switch back to pads. There are plenty of ultra-thin and absorbent pads on the market.
Best of luck!