Write
1. Insert blank DVD
2. Choose “Open in finder”
3. On the left hand side of finder window, select “Untitled DVD”
4. Drag stuffs that you want to write and drop them into that folder
5. Then “Burn” on the upper right corner of the finder window
Or use “Burn folder” as shown in this video
http://www.videojug.com/film/how-to-burn-a-dvd-on-a-mac
Copy
This website has nice screenshots and step-by-step explanation.
http://www.kenstone.net/fcp_homepage/making_dvd_copies.html