You can rotate either the image itself or the plane it is on. It is easiest to rotate the plane. Select it, then select Modify>Transformation Tools>Rotate Tool or simply select the rotate tool on the tool box on the left side of your screen. If the tool box is not there, you probably accidentally removed it. To make it appear, choose Display>UI Elements and make sure "Tool Box" has a check mark beside it. Anyway, to delete stuff simply select the object you want to delete and press delete on your keyboard. It's as simple as that.If you're new to Maya, I would highly recomend learning the basics first and hold off on the car model. There are free tutorials here at Simply Maya that you can download. Once you have mastered the basics, you should think about joining the VIP section for more advanced training. And as always, ask questions.