First and most importantly, why wont it burn?
The Disk Utility burns files. If you want to durn you Project file to an optical disc, then then create a disk image and drag your project file to the disk image you created. The the "Burn" option will become available. However, why do you wish to "back up" your project file? It cannot be played nor even opened without iMovie '08 and all of the source files used to create the project. If you are trying to create a DVD which can be played on a commercial DVD player, then you must files share your project as a "physical" file. Once a physical file has been created, it can then be save to an optical disc as either a "data" file or you can use iDVD to "author" a dVD which will play on a commercial DVD player.
2nd of all, with just basic iMovie, can I put a template on?
No, iMovie is a video editor.
When I put the CD disk utility shows up, what do I do after that?
Disk Utility is your current "default" application that automatically opens when you insert a disc. It will remain so until you change your preference or install another burning application (e.g., Toast) that can burn content and allow it to be your default.
I want to make it onto a DVD, so I can play it on the TV.
Then you have to use a DVD "authoring" application. DVD authoring applications are used to create menus, convert your iMovie edited files to multiplexed M2V/PCM (iDVD) or M2V/AC3 (Toast) content in VOB file containers, create BUP and IFO files and place everything in the VIDEO_TS folder used/read by the DVD player for playback on your TV. I.e., neither your iMovie projects nor the files it creates are directly playable by a DVD player. Use the iMovie '08 "Share" option to share your project to the Media Browser and then close iMovie '08. Open iDVD and select the type of DVD (standard or widescreen) that matches you iMovie project and select your "Media Browser" file from within iDVD. (You may want to view some of the iDVD tutorials to better understand how to do this.)