Hey Noelfy!
Thank you! Your questions are not stupid at all:-) I actually wasnt sure so I checked with Fotolia and yes you can sell it on other sites or you can use it as you are the copyright holder, however I found this disclaimer on Fotolia:
"If Fotolia becomes aware that a non exclusive contributor with a rank of “Emerald” or above is distributing any images, vectors or videos (the “Works”) through another stock agency or website (where at least some of such Works are the same as the Works being distributed through Fotolia), and if the pricing charged on such other stock agency or website for the downloading of any of such contributor’s Works are comparatively lower than the pricing charged on Fotolia for downloading Works of “White” ranking contributors, then, subject to applicable law, Fotolia reserves the right, at its discretion, to lower the pricing of any of such contributor's Works offered through Fotolia so as to match the pricing for the Works of “White” ranking contributors on Fotolia. Subject to applicable law, Fotolia reserves the right to inquire, from time to time, with any given contributor with a rank of “Emerald” or above as to whether such contributor is distributing any Works through any other stock agency or website, and such contributor shall promptly provide this information to Fotolia. For clarity, Fotolia is under no obligation to make any such inquiries."
I dunno how about the other websites, I use Fotolia most of the time :-)
Martina

@noelfy I think the key is the right tags. If you describe some picture just by its location, chances are very small. I would describe also emotions, culture etc so more people find you. I have very cheap small camera but my pictures sell anyway :D I usually play with them in Photoshop, sometimes coloring the sky blue etc. When you look at the most popular picture sold at Fotolia, you get some idea what works best.

Thank you! I will add it to the tips ;-)