How burn a video onto a disk? Help?

Okay. So i just watched something on youtube about how to converting it and stuff... So i downloaded "ConvertXtoDVD" thing and i tried putting my video onto the "Tree View"... And even though i keep putting it on, it won't show me it in the tree view. My video is a "Nero ShowTime" and i think its pretty long... Has about 25 chapters. Is it not showing because of its size or what? And if it is... what can i do? Anything else that i can do to burn the video onto my disk? ..