The process is
encode file
This generates 5 files
file.1
file.2
file.3
file.4
file.5
you can now delete the original file
You put the shares on 5 different USB drives and spread them out.
If you need to get the file back, you need any 3 of the 5 shares.
decode file.2 file.3 file.5
This generates the original file.
This means that if 1 share gets stolen, you can still recover the original file.
In fact, if any of the 5 are lost/stolen/broken, it is probably worth regenerating all 5.
The way I think it would work is that you would be prompted to insert the USB sticks one at a time.