Ok, boot the computer and insert the flash drive as before.
Then you need to go to the flash drive's directory by typing this;
Then list the directory by typing;
You should get a list containing all the files in the directory. One of those files should be, slacko-5.5-PAE.iso
If you don't see that file or don't get that far, report back here with what you do get.
If you see that file, then you're on the right track and can proceed.
cp slacko-5.5-PAE.iso ~/
This may take a while so be patient.
Now go to the home directory by typing;
Now we're going to make that usb flash drive a live Puppy usb.
Type the following;
dd if=slacko-5.5-PAE.iso of=/dev/sdb bs=1M
The first command un-mounts the flash drive.
The second command does a low level copy of the iso file and writes it to the raw flash drive. This will take a very long time and nothing will show that it's doing anything. When it finishes, it will print something about records in and out and the prompt will come back.
If the first command fails or gives an error, don't type the second command. Come back here first.
But if everything goes smoothly, then you will now have a bootable Puppy flash drive.
At this point, you need to reboot the computer and see if you can get puppy to boot.
report back and let us know what happened.