Baptism is a huge part of the body of Christ. Some churches create an entire service to celebrate this awesome day.
Jesus was baptized in the Jordan river by John the Baptist. There are scriptures in the bible that describe his soul being renewed. Following the ways of Jesus is part of the journey of believers.
Every church is different. Children are usually dedicated to God until they are considered old enough to make their own decisions. Parents and bible schools also explain the significance to kids at a young age to ensure they will be prepared. Other than that, there really no rules except having a willing heart.
A bathing suit underneath regular clothes is the easiest method to change after the dedication. Bringing a backpack, with a change of clothes and hygiene products is a great idea if you would like to do something right after hopping out of the water.
It was truly an amazing experience. The feeling of being renewed and strengthened is like no other. May God bless you with your baptism.