It's nice to help people learn, but there are two reason why you might not want to:
1. Company security and policy: Do you really want other users tinkering with the workstations and possibly messing things up? Do you know for sure if they are qualified/can handle doing so? And what time would it take out of THEIR work that they are supposed to be doing to do the extra work on the workstation?
2. Some users may want to learn, BUT, as with some folks I've worked with online, the just don't "get it". They will do something other than what you told them and come back and say "it don't work." But you won't know until 10 emails or an hour later that they didn't follow your instructions exactly. It's "oh, I did this and that because I thought it'd work." When approached why they didn't follow your instructions it's "Oh, I did. I told you it didn't work." and you have NO idea exactly WHAT they actually did! I've been in that position with a few people throughout the years I've had a web site online and had to help those who were having problems that others weren't.
I would say it's best to just leave them do their job and you do yours. Everyone is qualified and working on the job they are because they know how. When someone tries to "learn" another job, that can be a problem, especially if they are not getting professional training from a trainer that is used to handling problems those learning can encounter. And the employer also will have to want to have the particular person trained in that other area as well.
If someone asks, you could let them know that if they would like to learn, to ask their supervisor if they can enter a training program, because you're job description unfortunately doesn't allow you to train others, as much as you'd like to help. If they snare you with "how about when we're not working, you know... maybe you could slip me some info on our break and I can try it at lunch..." just reiterate that you are not allowed to do so (or if you are, just let them know you're (whatever job you do) and not a trainer for that job.
It can be sticky to deal with some of these folks, but there's ways to gracefully get out of it if you have to.
IF you DO decide to help out, be sure there's plenty of time, and before you do even that, be sure of the person's technical skill level and that it matches the task they will be performing. If they are underqualified, be sure you know how to get them up to qualification or ability to do the task (may have to write extra steps or information/explanations). If they are grossly underqualified, then you need to somehow gracefully get out of it.
Just be careful if you try and help. There can be snares with some that don't know much other than their own job. It's great to learn, and some pick up fast and become gurus. But there are some that just never "get it right".
Good luck. :)