. . . When I create film and is ready, what I have to do before save it to DVD-disc . . .
You need to use the Burn tab to select the type of disc, the menu system and burn the disc.
I would suggest you read the PDF manual available under Help for more information.
I would also advise you to burn to rewriteable disc first, DVD-RW or BD-RE, for final testing in a player, as you often find an error when viewed on a big screen.
Once the rewritable disc is OK this can then be copied to a permanent disc using disc burning software such as Nero or ImgBurn.