Don't worry
You need to place the link to the picture between [IMG] and [/IMG]. To obtain the link you need to rightclick on the picture and paste the "URL" that it will give you. If you want to upload a picture that is on your computer, you should upload it to a free hosting site (that's the easiest way to do it
). Most free hosting sites (like photobucket.com or tinypic.com usually provide the links for you
)
If I wasn't clear enough just let me know! I'll explain myself better