Possible Duplicate:
How do I update my TeX distribution?
How can I change the package repository?
Please help me to install packages. When I install the options for random repository package is not shown.
[Tex/LaTex] How to install titlesec and secsty packages?
installingmiktexpackages
Related Solutions
You can use the package manager for that. However, I would recommend you to update to MikTeX 2.9 if possible.
Then you can go to the Repository Menu and select Change Repository option.
After clicking next if you wish to have it updated from internet, you would get the list of available repositories.
Note that, an available repository can be offline temporarily such that you can't download packages or update them.
Yes, it is default behaviour of MiKTeX to install missing packages “on-the-fly”, but this can be changed in the Options dialogue. All in this way installed packages go into %APPDATA%\MiKTeX\<version>\ (<version> is 2.9 at time of writing), the MiKTeX variable is UserInstall. Since Windows Vista %APPDATA% resolves to C:\Users\<username>\AppData\Roaming, therefore your observation.
But this needs an active connection and a responding download mirror. At least one of these two things did not work in your case. If it was the mirror you can take a look on the CTAN mirror monitor Status of CTAN Mirrors, and if necessary in MiKTeX settings change the active mirror (MiKTeX Options, in tab “Packages” the first line shows the active MiKTeX repository and on the right you can change it).
I prefer to install all packages with the Package Manager, but this needs to be done on a regular basis, about once a week, and of course one needs enough disk space. In the rare cases, when I was asked for installation, I stopped this and ran the installation with the package manager. (Note, that this is different from, what is usually meant with “manual installation”! You already linked to the according question.)
All with the package manager installed packages go into the main MiKTeX tree (see Root 3 in your question), if you made the update in admin mode or in single user installation with writing rights in this folder. If you did a user mode installation packages will always be installed in UserInstall.
One would expect, that installation in admin mode goes into CommonInstall, what is the same folder in your case. But on my system this is not used, the folder, to whome CommonInstall points, does not exist!
Other related questions, at least partially:
Best Answer
I gather you use MiKTeX 2.8. (Aside: you should really consider updating your MiKTeX distribution to version 2.9!) To manually install packages -- rather than rely on MikTeX's built-in autoloader process -- bring up the "MikTeX Package Manager" program (under "All Programs -> MikTeX -> Maintenance"), search for and highlight (by clicking on) the lines that say "sectsty" and "titlesec", respectively, and click on the "+" (Plus) button. After a few minutes, the packages should be ready for you to work with.
Of course, this method requires you to have a connection to the Internet where your computer is not located behind some firewall. If you are behind some firewall, though, you may be out of luck until and unless you can get connected to the Internet differently.