Start the notebook and hit F7 to get the boot menu. (can be other f key, fo example F10 or F12)

see Boot menu hot key chart for most computers

Select the usb stick with the keyboard arrows up/down and hit enter.

Choose your rescue flavour with arrow down/up and hit enter:

Backup your current installation with redorescue:

Choose redorescue from grubmenu and hit enter.In the redurescue screen hit backup:

Choose your source drive. This should contain your current linux or windows or mac installation:

Redorescue will list all partitions, the must be checked all. Only no need to backup swap partition.

Next select destination drive. This will be the usb drive (in this case samsing). Select the biggest part of the drive:

Select folder: no need to do anything. Hit next

.

Name your backup. It's also good to date the backup:

Redorescue will make backup and put it on the external disk:

If there is a second harddisk in your pc, hit start again and also backup this second disk to the external ssd.

Recover backup to computer:

In Grub menu, again choose redorescue.

And hit the restore button:

Select your external ssd biggest space and hit next:

Select your backup (.redo) and hit ok:

You will get this, hit next:

Next select your source drive. This is the disk in your computer, with linux or windows installed.Hit next.

Redo rescue will select all partitions to recover, hit next:

Are you sure? Hit yes.

Redorescue will recover your system. If you had a second disk in your pc, you need to recover this also, or the computer will not start.

Hit start again and recover second disk.

If you want to make backups every month or so, be sure to order the samsung ssd that is big enough.