If you've tried and it fails it may be that the picture size is too large... I wanted to post a picture I took today but I can't because it's 4mb... I'll have to reduce it when I get back home.
You may need to store the picture somewhere online and post the link to it. I see that you're a standard member I think that's what you've got to do anyway, I think uploading pictures is a benefit for higher levels of forum membership
@RickS1K is correct, uploading photos natively is a Premier member benefit.
As a standard member, you?ll need to upload to a file hosting site of your choice and then post a link to it