Focus on the benefits of the talent show and what students can gain by joining. These could include an opportunity to perform into others, if there is a prize to be won etc. It is best to focus on things that your fellow classmates could gain by joining the talent show, and hopefully they will decide to sign up. Also making the piece interesting and different will also help to attract interest.
Tell the students about the positive side, here are some points you can say:
1.Meeting new people with similar interests. 2.Giving their talent a chance and exposure. 3.Seeing what type of talents they have and exploring themselves.