"but hey anyone can make stickers right?"
... actually, yes, but quality will vary greatly.
Back to the topic, which of you is more computer literate, you or your husband? Since he already has the install side down, YOU might want to become the designer so that you'll have less down time working around projects.
Since you flexi already, you might as well invest your time learning it. Eventually you'll most like grow into other programs. The others are right though, just about anyone can learn to use the software, but not everyone has the aesthetic sense to create something visually appealing. Do you have any family or friends with an artistic bent that you could tap into to help you get started? Having someone you know and trust and get on with would be great.
For formal training in the software then you're probably better off with the Adobe suite (Illustrator/Photoshop) as those are more readily available in classroom settings. Tutorials for the Corel Suite can be found online, but there really isn't much online nor in classrooms on any of the sign-making suites such as flexi. You may be able to get some training from the software vendor/distributors but thats iffy.
Forums are a good place to ask questions, just be thick-skinned about it. If answers like, RTFM get to you then forums may not be for you. If you can take a little bashing about your lack of experience/knowledge/whatever then you'll be fine in the forums.
BTW, the shop in work in during the day was started by people with zero signs and graphics experience. The designs were done by the owner and his brother, neither of whom were artists. The designs weren't great, but they were able to fill a niche of doing quick and simple, mostly text based, signs. It limited their customer base but they at least had customers. So it can be done... those that have put their blood, sweat, and tears into over several years may not like admitting it though.
Just be sure to keep striving to improve your quality and ability and don't settle for "good enough."
Best of luck.