by Howard Miller.
Not of Moodle. How did you install Moodle (I'm hoping you don't say via apt-get)? The instructions for backups are here - Site_backup.
Really, all you need is a dump of the database...
mysqldump -u root moodle >moodledb.sql
(substitute what your database is called for 'moodle' and moodledb.sql is the file you want to keep safe)
then...
zip -r moodledata.zip /path/to/moodledata
(substitute your moodledata path for /path/to/moodledata and keep moodledata.zip safe)