If you want to fill a 16:9 screen with active picture, you need to do what’s called a tilt & scan process. Roughly a third of your image will be copped and the remaining 2/3rds stretched horizontally to fill the full height. You also need to decide which 2/3rds of the image to keep as I doubt just taking out the middle section will look good composition wise. Usually a common top moved down just a bit seems to work for most shots.
Use the pan & scan effect found in the reformat tool. Read the User Guide but you will setting source to 4:3 and target to 16:9. From there you can choose which portion of the frame to keep. Set the render to HQ, it will take a while, but you will want the highest quality image when projected.
Keeping the 4:3 square in the middle of a 16:9 screen will keep the highest quality image.
Michael
anything 24fps