To start using Behold, you will need a GEDCOM file to open.
A GEDCOM file is a file your current genealogy program should be able to create. Usually, you will find a menu item in the File menu of your program that will say something like "Export GEDCOM file". The file will usually be saved as a file whose name ends with the .ged extension. 
Once you have a GEDCOM file (it can be yours, or one given to you, or one you got from the Internet, or one of the sample GEDCOM files that were included with Behold), you can start Behold.  Use the "Open" command from the file menu and use that to find and open your GEDCOM file.
Behold will process the GEDCOM file and present you with a split screen containing a TreeView and the Everything Report.
You'll quickly see that Behold is designed to look and feel like any standard Windows application. Most operations should be obvious. Clicking on a tree item brings that item into view. Clicking on a hyperlink takes you to that link. Most keys work as you expect: Page Up, Page Down, Copy and Paste, and there's a Find tool that works like you're used to, and standard menus and toolbar icons that you'll recognize.
The Everything Report is the real gem in Behold. Here you'll see your family all laid out for you, in one comprehensive indexed report.
There are many options available to customize this report to exactly meet your needs, but you should read the Behold Tutorial to learn more about that. It covers most topics and gives a good overview of what you can do with Behold. 
Behold is very different from all other genealogy programs. There are no forms to enter data into. There are no reports to generate. Behold is designed to look and feel like a word processor, such as Microsoft Word. The Everything Report is the report. When Version 2.0 comes out, you will be able to edit and add data directly simply by typing it where you want - and that will make your data entry a hundred times easier.
So while you try Behold out, you'll see ways it can help you do your genealogy research that your current genealogy program cannot.
When you're ready for a more detailed look at Behold, try the Tutorial (about 60 minutes). It begins on the next page ...