More information is available at the community portal. You may ask questions at the help desk, village pump or on IRC channel #wikimedia-commons (webchat). You can also contact an administrator on their talk page. If you have a specific copyright question, ask at the copyright village pump.
Please do not overwrite files
I noticed that you uploaded a file using the name File:Danielsanchez.jpg. A file by this name already existed on Commons. Overwriting an existing file should not be done except when making minor, uncontroversial corrections, so the file has been restored to its previous version. If the file that you attempted to upload is within our project scope and is in the public domain or published under a free license, please upload it again under a different name. Thank you.
For more information, please see Commons:Overwriting files.