I am interested in Becoming Baptized at Pendleton First. 

The day of the Baptismal head on down to the MPR after the service and you can change in the restrooms there. 
Bring modest shorts/capris and a t-shirt to be baptized in (not white). Bring a towel and plastic bag for your wet things.
When you are ready, go ahead and take a seat and you will be called up when it is your turn.