Is this normal?!

So I am 15 and really wanted to try some but stuff. So I went to the bathroom before hand and let everything out. ( lol that sounds weird but yea) and then I made sure I was relaxed and sucked my little finger then slowly ut it in. It was weird at first then I relaxed more and it started to feel really nice. But I had the grosses feeling to I was about to do a number two. So I stopped and when I pulled it out I had a bit of poo on my finger. I washed it straight away. But how do make sure that doesn’t happen again?