Installer apt -get sous ubuntu

Merci pour l'infos.

Je souhaite installer x-mplayer2, mais lorsque je fais apt -get install x-mplayer2, il m'affiche ceci:

E: Impossible d'ouvrir le fichier verrou /var/lib/dpkg/lock - open (13 Permission non accordée)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?
gabriel@Gabriel:~$ apt -get install x-mplayer2
apt: invalid flag: -get
Usage: apt <apt and javac options> <source files>
where apt options include:
-classpath <path> Specify where to find user class files and annotation processor factories
-cp <path> Specify where to find user class files and annotation processor factories
-d <path> Specify where to place processor and javac generated class files
-s <path> Specify where to place processor generated source files
-source <release> Provide source compatibility with specified release
-version Version information
-help Print a synopsis of standard options; use javac -help for more options
-X Print a synopsis of nonstandard options
-J<flag> Pass <flag> directly to the runtime system
-A[key[=value]] Options to pass to annotation processors
-nocompile Do not compile source files to class files
-print Print out textual representation of specified types
-factorypath <path> Specify where to find annotation processor factories
-factory <class> Name of AnnotationProcessorFactory to use; bypasses default discovery process
See javac -help for information on javac options.

c'est la que je blocque.

Merci de m'aider.

Merci,

Mais il m'affiche ceci:

root@Gabriel:~# apt-get install x-mplayer2
Lecture des listes de paquets... Fait
Construction de l'arbre des dépendances
Lecture des informations d'état... Fait
E: Impossible de trouver le paquet x-mplayer2