Hi,
just have a look at the "license" section of the image description page on Commons. If you will behave compliant to these conditions you are allowed to use them, of course: 
Just cite the source (wikimedia commons) and my username accordingly. 
And you must provide your work under a license with same/similar conditions.
For more informations on the license terms, see .
I would appreciate to get an information which image you have used. Thanks for asking!