Tony ... Really depends on the forum rules; some do allow small jpg photos to be imbedded or attached while others worry about malware bots being included inside the pictures and they don't allow photos.....
Those that do usually have posted somewhere in their site info the way and type of pics they would allow, if they do so.... Usually a good way is having that photo stored on an upload to a photo storage site like Photobucket, where the picture is assigned an image url... a web address preceeded with

..... YOu would just copy that address and then go back and insert or attach the image address into the forum.... Or you can save the image to your computer and then at the forum click to add an image or file, browse to the storage location on your computer, click Open and then upload it to the forum. As long as you don't erase or move that photo, it is visible on the forum..... That is the benefit to saving them to a web hosting site and even if you were to change computers, the picture is still located at the web hosting site.... To insert an image here look at the 2nd line of icons on the editor at the top of the page and the 2nd icon is the link to Insert Image.... you can browse to the address on your computer or the hosting site where the picture is saved, upload it between the

and the picture should be in your posting..... At those forums only allowing attachments, the picture address would be the attachment and when someone clicked on the attachment link they would be taken to the web hosting site to see the picture.....