Click on the red Update Manager arrow.

When the Update Manager starts it displays all available sofware updates.

Click Install Updates. Enter your password in the dialog box.
When udating is finished close the Update Manager and restart the virtual machine by
clicking on the red power symbol in the upper right corner and then Restart.

Double click on the file pwr46_4.6.0-6ubuntu_i386.deb on the desktop.

Click Install Package. Enter your password in the dialog box.
If the installation completes successfully, skip down to step 13.

If the installation fails, which might be the case behind a proxy server, you can download the
missing packages manually using Synaptic.
Click Details in the Package Installer to se the list of missing packages (dependecies).

Start Synaptic from System->Administration->Synaptic Package Manager.
Find the missing packages in Synaptic by clicking in the list and then type in the package name.

Add the package by right clicking on it and selecting Mark for installation.

If the dialog Mark additional changes? appears, accept the changes.

Some of the packages in the Details list might already be marked because many packages
depends on them.
Repeat the above until all missing packages from the Details list are marked for installation in Synaptic.

Close the Details list and the Package Installer when the marking is all done.

Click Apply in Synaptic to start download and installation of the packages.