I checked the TUTORIAL section and this is one important thread that is missing there. A refer for the newbies willing to contribute masala/non-masala stuff on MB :
Just host the pic from you computer in a good imagehoster say tinypic.com. Open the link n click "Browse" and select the pic from your comp. n then click "Upload". After the pic is uploaded,just add the image link within image tags ([img] [/img]) in this format:
[img] "Your image Link"[/img]
You can also use the image link on the reply box to add the tags to the link.
MAKE SURE YOU ARE WITHIN THE MB Posting Guidelines WHILE POSTING PIX.
Then post your reply to find it as inline !!
You can get a huge list of imagehosting sites from this post by White_Raven !!