I downloaded it but I am unsure of how to install it?
As you give no real detail I will presume that this is a new install from an iso that was generated after June 2011.
Use a ethernet connection and launch synaptic , click reload, mark all , apply, apply wait for the update to finish after this your install will be up to date.
then in synaptic use the search facility to locate the package Texstar has highlighted right click then mark for install and apply, then apply . this installs the package.
After this reboot and set up the wireless.
Its also worth pointing out that is this is the "bonsai" version of the open box iso - it is intended for the more advanced user and maybe (is) missing what the main KDE release has installed on quite a few levels.
Please read teh links supplied as it will help you formulate any further posts as to which information is relevant and required