You didn’t miss anything other than forum etiquite.
You never told us how the system was originally installed, you post a link to some Digium instructions that may or may not apply (as I rule I don’t follow links out of post).
In short you never asked a question. There are some folks in here that will try to help if you botch up an Asterisk issue, however this is a FreePBX forum.
If you don’t know how to download and install Asterisk, or understand DAHDI and other dependencies it is best to simply install using our distro or one of the other good distro’s. That’s why distro’s exist, to provide a method for folks that don’t have Linux experience to enjoy the FreePBX experience.
I agree with Tony, your distribution does not support an upgrade path. It has to be done manually. If you only know the web interface you will not have a good experience trying to download Asterisk and solve all the dependency issues.
You may consider using our paid support. One of the engineers would log on to your box and upgrade everything on your system needed to support Asterisk 1.8 and FreePBX 2.10.
Upgrading Asterisk using something like Asterisk Now is not something that FreePBX forumns can usually address as this is 100% outside of FreePBX. If you were using the FreePBX Distro or PBXiaF we both provide upgrade paths for asterisk/dahdi and the kernel.