Welcome to the forum, Marcus. I'm glad you found this great hobby.
This site employs a notoriously convoluted method of posting photos. You need to upload your photos to a photo hosting site such as fotki or imgur. Once that is done, you copy the [IMG/] code for that photo from the hosting site, then paste it into your reply on the forum. There is some more info in the Community Assistance part of the forum near the bottom of the main forum page. Good luck, and enjoy the forum.