image and deployment

Good Morning I have read the Disk imaging article on this site by MACSHOME Disk Imaging made easy I guess I’m to new to Mac because I don’t understand real well. So here is a few questions I have #4. says Once disk utility finishes up mounting the image, open a Terminal session. Does this mean make the image first then sudo rm files listed from the image made? #5 says un-mount the image and then convert it to a compressed image. What does it mean by un-mount image. I am new to this and have lots to learn this site is wonderful. Does anybody have any insight on Deployment? What I would like to do is get some images on the server and then deploy them to a lab with 30 iMac’s I work in a school and this would save me a lot of time. Sorry to be so dumb about this I don’t know if it is just me but Apple’s documentation is very windy. Thank You 🙁