It was not too long ago I was asking the same question.
First, you are going to need at least 5 postings before you can do anything with photos.
As far as actually posting photos there are instructions in the Welcome Forum. Look under "About this board" and find the "Tips for posting Photos".
I have only attached images to my postings so far so I know those instructions work.
Hope this works for you. Good Luck!
I’m retired and my time is my own – as long as my wife allows it!