My choir organized a musical concert for the purpose of buying some musical instruments and I was assigned to give a welcome speech on the of the event?

So what's the question? Telling us about the situation is not a question. Are you asking how to write a welcome to this event? 

Thank you so much for coming to our concert featuring the Mayberry High School band. As you might be aware, this concert is to help our band raise money for new instruments. So we want to thank you for coming to support our cause. Enjoy the music!