The website JG found is a good one and gives you all the basic information. It isn't a big scary thing... It's really very simple. The object is to get the little cotton plug as far up in you as you can, and there's no worries because your body won't let it go any further than it should. You can't do any damage to yourself with a tampon. Start with the smallest size on the market, and use a lubricant to help it slide more easily until you get the hang of it. When I first learned, I found it was easiest to insert with one foot perched up high (on the toilet set or even the back of the toilet), the hardest part is getting the angle right, once you figure that out it's a breeze... Don't be afraid.. Tampons will make your life a whole lot easier in the long run.
Can I just mention here that you shouldn't leave the tampon in too long in between changes very rarely people have experienced toxic shock syndrome by forgetting to remove it or leaving in far too long if you change the tampon every 2 to 4 hours you will be fine didn't want to scare you here because it is very rare if you follow correct advise
Clearly, I do not know by experience myself, but I did happen to find an article on How to Use a Tampon....hope that helps.
First you need to find the right size for your body and flow of your menstrual. Once you figure out the correct size for you take the paper off the tampon & insert the tampon as far as it will go as long as its comfortable for you the string has to hang out so that you can pull it out when its time to change. Please dispose of plastic or cardboard application properly. Do not flush. Be sure to wrap tampon up really good in dispose, because no one wants to see your personal business.
Everyone's got it covered here. All I can add is that when I was your age I had very heavy periods and had to use 2 yes 2 of the heaviest flow tampons they made. YES you can insert 2 tampons at once one on top of the other. If you find one of the biggest ones leaks. But become comfortable at inserting one first. Then after one is in( put it ALL THE WAY IN ) put another one in right after it.
Um well you stick the applicator up into the vagina and if it feels uncomfortable just pull it out before pushing in the tampon. Make sure its comfortable to the point you don't feel it then your golden to push in the tampon!