It need to be hosted on an on-line photo server like PhotoBucket first so it has a URL (web address). Then you can include a link to it in a post or link to it directly so it shows up as part of the message.
Ziggy go to the link above and join for free and like Mike said your pictures has to be stored on a site like photo bucket or even your own web server space but I like the photo bucket myself ok after you get an account then myself I would make several different album's to store my photo's in.
Most people just put's them all in the open but if you upload a lot of them then it is nice to keep the certian photo's seperate in different album's.
Ok all you do is go to the Upload section in the upper right side of the photo bucket and click browse and then you can loacte the photo from your hard drive and you will hit open and it will paste the link to the photo in the brose box,when you are ready then hit upload and it depends on how big it is but it will give a graph on the uploading progress,after you have it stored then you will see 3 boxes below the photo and if you want to post 1 picture to the post then use the first link which is the URL and copy and paste it into the post you made put it the Image URL: box at the top of the post.
Ok if you want to do multi photo's then use the 2nd link below the photo which is the HTML Tag and copy and paste this into the text area of the post don't put it in the Image URL box.
You can copy and paste as many of the HTML Tag links as you want in the body of the post but make sure you hit the enter button at least 2 times after you paste the link this is so it will show a break between the photo and your text you are typing.
Ok I never use the IMG code link at all holler if you need to.