As far as I know newbies aren't allowed to post images here in bitcointalk forum, that's why he can only see link in his post rather than images. Although that is the case, there is an option wherein a newbie will be allowed to have that privilege but he has to pay. After that, he will become a copper member, able to post images here in the forum. OP should refer into meta about this, there are detailed guide on how to be one there.
That must be it! But I don't see why I can't post images when I use the img codes. See: