The additional content is important to install. It includes dozens of disc templates, title templates and themes. You really do want to install it.
If you poke around on the main installation disc, you should find a PDF of the user manual. There's also a pretty thorough Help file. There are also lots of tutorials via the Inspiration Browser on Photoshop.com, so be sure to sign up for it too.
And if you want a simple, step by step guide to all of the tools in the program, there's always my books.
Disk 1: PSE10 and PRE10 for Windows (32-bit)
Disk 2: PSE10 and PRE10 for Windows 7 (64-bit)
Disk 3: PSE10 and PRE 10 for Mac OS
Disk 4: Content for all Windows versions
Disk 5: Content for MAC OS
Are you installing on a Mac ? If not then it's Disk 4 you need to install to get the additional content.
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