Some girls (and grown women) can feel embarrassed and uneasy about changing clothes in a locker room for the first time, being completely naked, and showering in a communal shower, such as after swim team practice at school.
First, don’t worry. Everyone in the locker room is basically doing the same thing, and there is nothing to be ashamed of because there are girls there, and you all look basically the same and have the same private parts.
Keep your change of clothes and a towel ready for you to put on and use. Leave your shirt on while you change your shorts or pants. Keep your eyes downward if that makes you feel more comfortable.Most of the other girls are probably just like you and nervous about being naked in front of other girls. When you take off your undergarments, face away from other girls as much as you can if it makes you feel more comfortable. You can be quiet and not banter (talk) so as not to cause other girls to pay attention to you. Act like you do when you change and shower at home.
After a few times, especially the first time, it won't bug you as much, and you probably won’t think twice about being nude in the locker room with other girls.