You can upload your photo at Imgur.com and copy the direct link. When you posting your post, if you not familiar with markdown syntax, switch to editor mode and click on the image icon and paste your image link. After clicking the tick sign, you image should appear.
The Steemit image proxy servers were going back and forth yesterday between working and not, and then switched back to just having the original hoster with the image. I uploaded some images to imgur and these became broken because imgur banned Steemit from displaying its images. If the proxy server stays up though, they will continue to work.
imgur.com doesn't seem to be a good choice. Some recommendations can be found in this post: https://steemit.com/steemit/@primus/best-3-image-hosting-sites-for-steem
Thank you