For your question, you can drop your photo to the link: https://imgsafe.org/
After that, copy the link the website generate to your post. That's it!

As a beginner, I also think you will need some knowledge on formating your post in Steemit. Here is a link for the tutorial: https://steemit.com/steemiteducation/@sweetorange/steemit-text-code-formatting-tutorial-include-image-warp-text