All standard classrooms have a lectern through which you can control the presentation technologies: computer, projector, microphone, visualiser, external laptop connection.
And in some spaces there can be a Blue Ray/DVD player, a ceiling mounted video camera, a web cam or integrated computer monitor camera.
Some classroom lecterns have a push button controller.
Others have a touch screen controller.
There is no central training provided for the operation of the classroom presentation technologies.
Each room will have a laminated instruction sheet giving basic instructions as to how to operate the equipment. It is recommended that you spend some time in a classroom before you officially begin teaching, familiarising yourself with the equipment. If possible you might consider asking one of your colleagues to show you how to use the equipment.