Jim's recommendation to use the gui is a good one. Often the way Linux commands are written is very confusing. I think this is what is happening.
As root, check who owns /dev/ttyUSB0.
It should say root:dialout - if its something other than dialout, you have to be in that group.
sudo ls -l /dev/ttyUSB0\
Does it say root:dialout? If so go to next step, if it doesn't write an email to the group.
Now let's add user holmzie to the dialout group, we have to do that as root.
sudo usermod -a -G dialout holmzie
If it says usermod command isn't installed, install it.
Otherwise, if no errors, reboot and then type groups in terminal and you should have dialout in the results.
At the user prompt type: groups
My system - which is different that yours, responds: users lp floppy dialout audio video cdrom plugdev power netdev scanner sudo
But you will see dialout there.
73 DR N1EA