can i please get a speech for becoming school captain?

or cultural leader or house captain?

Here is a sample for your reference. You are expected to continue with your own ideas and perceptions. 

Hello everyone. I am very grateful to my honourable Principal sir and teachers who find me worthy of this post. I know and completely understand that this post comes with a lot of responsibilities and duties to be fulfilled. I would try my level best to make this school a place with no complaints and no demands. The school captain position involves being a voice for the students and a face for the college.My task is to represent the student population at meetings of the school council. There I get to voice the needs, concerns or issues of the young people at our school. These meetings are held monthly and are a way of improving the college. This aspect of the role is probably the most important. This is because for a lot of students, school can be a real chore, especially in the later years. So anything I can do as school captain to make the experience more bearable is very significant. (to be continued on one's own discretion.)