That is to be configured from "Brightness and lock" (in the "System settings"); Could you open a terminal, type 'sudo apt-get upgrade', enter your password when it is asked, and post here the output of the command?
If you do not specifically want the LXDE desktop environment (for instance, if you do not even know what it is) and if your computer is recent enough (it has at least 2 GB of RAM), then go for the "normal" edition of Trisquel. You can install the support for whatever languages you want. You do that from "Language support" (or something like that) in the "System settings".
