How can I post Images With gallery

I have created a portrait style advertisement for my website and would like to make a thread for Arc Raiders although Im not sure how to get the image to fill the post area, It is only shown as a small preview, I would also like to show a few menu previews as a gallery and I dont know how to post Images, from what a read, I have to be a premium member, I just purchased the 1-year membership and I still dont see any options to post the image as a gallery, I will attach a image to the post to give a little context.[Only registered and activated users can see links. Click Here To Register...]

[IMG=expandable: 1]IMG URL[/IMG]
Try like this :)

Can confirm — newer accounts often see the notice that image/gallery embeds stay locked until you hit the activity requirement (or upgrade to Premium).

Drewfire's expandable IMG tip is the right approach once embeds unlock:
Until then, keep posting normally so the account unlocks that feature.

As far as I remember, the images should show up normally once you have 20 posts. Could be wrong though. So I guess you’re only one post away.