@Quwasan If you've already posted one gallery photo, and you want to link a second photo, the best way to handle this is to upload the second image to the same gallery and then add the second image as a comment on your first image.
Open the image (in Arachnoboards) that you want to embed.
Copy the code in "Share BB (With Thumbnail) Code" or "Share BB GALLERY Code." (Both of these options allow the user to click the image for a link to the source.)
Paste the code where you want the image to be in your forum post, gallery comments, or conversations.