“Stand up to bullies! Don’t let them tell you what to do.” That’s the wisdom that Bannon Beaty, 10, has gained from his participation in a production of “The Rainbow Sea,” a musical that will be performed by 32 enthusiastic youngsters of the St. John School of the Arts Summer Camp. The sole scheduled performance will take place today. The show, which was written by Andrea Green, a composer, playwright and educator, was created in 1992, but its message of inclusivity is still relevant today. Admission is $10 for adults and is free for children 12 and under.