Search and install the plugin using the Extension Manager. Refer to Plugins on how to install plugins manually.

Every mod (that is Minecraft Forge's way of talking about extensions) has its own sub-space in the wiki. Every mod's sub-space is located within the root space :mods:. Every image of a block or item is named exactly like its description page in the wiki. And is provided as PNG.

Vanilla diamond item link will be:

<mcitem>minecraft:diamond</mcitem>

As noted above you should have diamond.png uploaded as mods:minecraft:diamond.png and a corresponding page located at mods:minecraft:diamond.

Example of an item links to existing item and missing item are on the picture below.

You can set the following:

• Show icon or not
• Size of icon
• Make item link bold or not