Upload a screenshot from a software program under a free license:
You have to make sure that all parts of the screenshot are under a free license. See Commons:Screenshots for more information.
On Wikimedia Commons fair use screenshots of proprietary software are not allowed and will be deleted!
If the file you want to upload is not a screenshot, use one of the other upload forms.
Select the open source / free software license used by the software project:
If you are unsure whether the screenshot is really free, then it is better to ask at Commons:Help desk first.