Short Answer 
To access hidden channels on Discord, first log into the application and select the relevant server. Then, click the downward arrow next to the server name to access its settings, and look for locked categories at the bottom of the channel list, clicking on the lock icon to reveal the hidden channels.
Step 1: Open Discord and Navigate to the Server
Begin by launching the Discord application or website and signing in with your account credentials. Once logged in, locate the server on the left side of your screen where the hidden channel is present. This is essential as hidden channels are only accessible within specific servers.
Step 2: Access Server Settings
Next, click on the downward arrow next to the server name at the top of the channel list. This action will expand the server’s options and channels, allowing you to see more details. It’s crucial to check for any locked categories that indicate the presence of hidden channels.
Step 3: Reveal Hidden Channels
Scroll down to the bottom of the channel list and identify any category that displays a lock icon. This icon signifies that there are hidden channels within that category. Click on the lock icon to unveil the hidden channels, making them visible for you to access and participate in.