Hi Jen, Put the photo of your card somewhere on the internet. (blog, pinterest, some photo-site as photobucket or some like this) Copy the place of your photo.
Go to the messageboard. do "reply". You see a lot of little images at the top of the field where you type your text. Click the 6th from right. When you do this you see a field where you can put the url of your picture. Do "insert image". Type your text. Before "create post", you can see if you did it good: do preview. When you dit it the good way you can see your photo. Sometimes you see your photo is too big, you can resize it (less pixels) in photoshop or some other program and try again. Success.