Instructions
Navigate to the site of the private server you want to connect to. There are several lists located online that rank the top 100 Grand Chase private servers, most of which forward you to the site's web page (see Resources).
Download and install the client of "Grand Chase" required to play on the server. Typically, each site includes whatever form of software is required to play on its server from its website. These clients already have the correct version installed and will automatically connect to the private server.
Start the game to connect to the private server. Once the game loads, you will be able to access and utilize files that are banned on newer versions of the game.