If you want to hide in plain sight, meaning there is no social networking attached, go to
postimage.io make an account and start uploading. You will want to use the "direct link" when you post your pics here so they show up without ads. Once you upload a pic and copy the direct link to your clipboard, come here, hit the little picture button up at the top, its on the right of the smiley face, and then paste your link into the dialogue box that opens up and asks for it.
Post image also has a little screen capture tool you can download and install so that when you hit your "print screen" button it gives you some powerful features to easily do a screen capture of any size and edit it like adding arrows or circles to point things out or even text.