#* If editing in visual mode, double-click the gallery in the appropriate section (or click once to select it and then click the "Edit" button that appears), then click "+ Add new image" at the bottom-left of the popup window. In the search box, type in the filename of the image, including the filename extension. When the image appears, click it. It will join the others in the column on the left; drag it to the appropriate alphabetical position. Don't close the popup window yet.
# Fill in the info:
#* If editing in source mode,
replace <code>FILENAME</code> with the name of the image you uploaded, such as <code>File:512.jpg</code> or <code>File:Red hacksaw.jpg</code>, and replace <code>TOOLDESCRIPTION</code> (both times, identically) with the title of the page you created, such as <code>link=Hacksaw, 12", red</code> and <code><nowiki>[[ Hacksaw, 12", red]]</nowiki></code> or <code>link=Hacksaw, 12", red ID:512</code> and <code><nowiki>[[Hacksaw, 12", red ID:512]]</nowiki></code>. Be careful to not delete the pipes (<code>|</code>), and make sure there are no spaces between the second pipe and the beginning of the link code (<code><nowiki>[[</nowiki></code>).
#* If editing in visual mode, click the link button (with the chain icon) at the top of the caption field below the image on the right side of the popup window. Start typing the title of the page you created, and click it when it appears in the suggestions. Now click the blue "Apply changes" button at the top-right of the popup window. Editing visually, you can't set the <code>link=</code> parameter; somebody else might do that, or you can add it yourself by editing again in source mode.
# If editing in source mode, click the "Show preview" button at the bottom of the editor to check that your addition appears correctly. (In visual mode, the editor itself serves as the preview.) If not, try to fix it so it does. If you can't, proceed anyway, and somebody else will probably fix it soon.