Hi Fsanterre! We're so happy you wanted to play to learn, as a friendly and fun way to get into our community and mission. I think these links might be helpful to you as you get started.
In English, unlike in French, references typically go after the punctuation, not before...
For consistency within the articles, you're better off using the existing templates which do all the formatting for you, ex., as done here, {{cite web}} and {{cite book}}.
File permission problem with File:Sarah M. Pritchard.jpg[edit]
Thanks for uploading File:Sarah M. Pritchard.jpg. I noticed that while you provided a valid copyright licensing tag, there is no proof that the creator of the file has agreed to release it under the given license.
If you are the copyright holder for this media entirely yourself but have previously published it elsewhere (especially online), please either
make a note permitting reuse under the CC BY-SA or another acceptable free license (see this list) at the site of the original publication; or
Send an email from an address associated with the original publication to permissions-en@wikimedia.org, stating your ownership of the material and your intention to publish it under a free license. You can find a sample permission letter here. If you take this step, add {{permission pending}} to the file description page to prevent premature deletion.
If you did not create it entirely yourself, please ask the person who created the file to take one of the two steps listed above, or if the owner of the file has already given their permission to you via email, please forward that email to permissions-en@wikimedia.org.