If you want to back up the whole system including the system folders like /var, /usr, and /etc, you'll need to do more than just installing some backup software. Backing up a running system is problematic unless you do the right things to enable it to happen reliably.
Either you'll need to reboot using a CD or external drive or another OS on the same machine so that the partitions and files you want to back up aren't in use during the backup process, or you'll need to use a filesystem setup that has snapshot capabilities, such as LVM and/or btrfs. A true full system backup would also include backing up the MBR, not just the files.
If you really want a full system backup, it won't be quick and easy. Do you really need that level of backup? Maybe all you really need is to back up specific folders in your home directory?