The change of class cadres is very common. You should communicate with your counselor first and listen to his opinion. As for the form, it is generally to inform the students about the general election first, so that those students who are interested in running for the election can be prepared. Secondly, at the beginning of the election, let those students who are participating in the election give speeches. Talking about your own ideas and other issues is equivalent to a campaign speech. Voting must be by secret ballot.

I hope my suggestion is helpful to you.