Disk Utility is for burning disk images like dmg, cdr and iso as well as the ordinary disk management stuff (partitioning, etc.).
If you want to burn files you can do that via Finder. If it is only a selection (1 or more items) you want to burn to disc you can make this selection in Finder then right click and choose "burn" in the context menu.
You can also create a burn folder which you can use to drop any file/folder you want on the disc. If you then right click that burn folder you can burn its contents to disc. Unfortunately you need to create a burn folder from the Finder menu (File > New burn folder).
The easiest solution to me would be an open source and freeware app called
Burn. You can burn iso images, easily drag files/folders and then burn them to disc all in 1 app. If you want to do that in a more fancier way you can buy Roxio's Toast.
