My period is wrong? And tampon help?

Ok so I ended my last one on may 14 and I'm usually I start it every 16-17 days but only once it's been 22 days? I'm going to Florida tomorrow and I'm trying tampons for the first time and I only have 2 without the instructions inside so how can I put it in and also how can I spare going to the beach and parasailing with 2 tampons how do I use it wisely? Does it hurt? I don't have a mom or sister I live with all boys please help my name is heather and I'm 14 never used a tampon n I dont have the instructions? What is the best position. I'm scared wht if it gets sticks or slips out! :( please help I am freaking out!