Help:FAQ
Why can't I create new pages / upload files?
In order to create new pages or upload files, you need to have an account and become autoconfirmed. This role is automatically given to your account when it is at least three days (72 hours) old and has made at least 5 edits.
I uploaded a new version of an image, but it didn't change or it looks stretched. Why?
https://shouldiblamecaching.com/
Your browser downloads images in order to display them on a webpage, and in order to reduce load times, it does not check to see if the image has updated unless you force it to. On most browsers, this can be done by pressing the refresh button while holding Ctrl (or Command on macOS). See Wikipedia:Bypass your cache for more information.
What are those red links that begin with "Template:" for?
That happens if a page attempts to call a template but the template hasn't been created yet. Missing templates are actively being worked on, so the red text should go away and start working properly once the template is complete.