256GB usb flash drive??? Wow! My first thought was it must be a fake, so no wonder it ran out of room, but I see they're now about £60. Not cheap, but I guess that's progress.
Well, let's take these points one at a time.
1. "Made decision on the Linux os I wanted to test drive". Grand, which one did you choose?
2. "...not a totally simple task to accomplish". It certainly isn't, the first time. Much like riding a bike or driving a car, though after a while it becomes a breeze.
I'd strongly recommend starting by getting an old desktop or laptop with at least 1GB or ram (preferably 2GB) and exploring Linux on that. Then you know your precious Windows system is completely out of the picture, no risks.
3. "I tried to back up everything and was told I ran out of space". You need to tell us more about how you did that backup, and what your objectives were. E.g. "I need to save my docs/pics but if my pc utterly dies I'll buy a new one and buy the applications I use". Or "I want a complete image of my hard drive, so I can restore the whole system to its current state if the ball-bearings fall out of my drive". And yes Virginia, hard drives do sometimes do that! Though they fail in other ways too, and these days you can reckon that unless you pay extra for premium grade enterprise drives they're pretty likely to fail within 5 years.
I wish I had a dollar for every time I've heard "No, I haven't copied my pictures anywhere else, and at the end of each holiday I reformat my camera card because I'm too cheap to spend a fiver on another one!". Or words to that effect!
Now Burgy, I'm delighted you're resurrecting this thread and I'm sure all us happy Linux users will be rooting for you and looking forward to another convert, but, frankly, you've been a rabbit in the headlights, haven't you!
And entirely understandably so, I'm not knocking you at all for that.
That's why I tell people there are only two successful strategies for most people: either
a) find a local Linux user group, who are sure to be friendly and welcoming, hang around them for a while to figure which ones are full of BS and not going to be much help, which ones are going to be "flying fingers" guys (they fix your problems, but they do it so fast you never learn a damn thing) and which are the ones with a bit of patience.
Failing that, because perhaps you're out in the boonies,
b) get an old pc to take your first steps on. Ask around, many people have one in the attic and it'll make them feel good to pass it on to someone who has a use for it. Preferably a pc that's 5 or 6 years old, not 10/15. Though with specialised Linux distros and for special purposes, even those can be handy, e.g. for several years I ran an OpenVPN server on a Pentium III 550MHz box! But that would be hopeless these days for a desktop, you need something with at least 1GB, preferably 2GB.
Very best of luck, keep telling us how you progress.