*Tampon period help!!*

I'm going to camp in a few hrs and I just starred my period and ik we will be swimming and have water activities. I still have yet to succeed in putting in a tampon. Idk what I'm doing wrong or what but I try and can't get it. It's not comfortable putting it in ( not even all in) idk what to do. Idk what I'm doing wrong or why it hurts to do it. I'm relaxed and pointing towards my back. Idk. Any advice?? Or how can I wear a pad when in water??