I don't recommend watching the tutorials offered by Sibelius if you are in a rush. The ones I've looked at were a little lengthy and did not cover the basics all at once. Take a look through this guide for the basics and google any specific questions as they come up. The Sibelius documentation is good and a quick google search will tell you basically everything you need. Furthermore, the program is more intuitive than Finale so you are more likely to find what you are looking for just by glancing through the menus and palettes than you are with Finale.