The RankCapes client mod is required for the player connecting to RankCapes servers to see their cape. The plugin sends the cape textures and tells the client which capes it has access to, as well as the other players' capes. Currently there is only a Minecraft Forge version available. Installation and use is simple.
Installation
To install the mod, first install Minecraft Forge to your client. There are multiple tutorials for doing this. I recommend this one. Next download the RankCapesForge mod from here and copy it to the .minecraft/mods/ folder. Thats it! Fire up Mincraft and join a RankCapes equipped server and enjoy!
Usage
Once installed, connect to a server that has RankCapes installed. Once connected, if you previously had a cape, it will show up. Press F5 to go into 3rd person view. To change your cape, press 'C', and the cape change GUI will come up.
This GUI shows all the capes that are available to you. Clicking any cape button will show you a preview. If you close the GUI without pressing the "Set" button, your cape will revert back to the one you had on before you opened the GUI. Pressing "Set" will change your cape to the selected one in the GUI. Next to the "Set" button are the previous page and next page buttons. If you have more then 4 capes available to you, they will be on another page.