Click on the word “Members” then find the member you wish to contact (you can use the search function) click on their name and then choose “private message”. Please note that if you choose “public message” everyone can read what you say.
It seems that the problem with posting pictures was down to user permission. I have upgraded all users to “author” to solve the problem.
Just paste your picture on any new line If you want to continue with text under the picture leave a blank line between your text for the picture.