How to install Envy Client
How to open ClickGUI
You can press RSHIFT (right shift) to open the ClickGUI. There you will also find the console.
How to use commands?
Type help in the console part of the ClickGUI.
How to use the TabGUI?
Open the console then type t hud. Now you can use your arrow keys to navigate the TabGUI.
Why does Envy Client crash when I start it?
Make sure you are on the latest version of Envy Client. If it still crashes delete the Envy folder in .minecraft. This should fix the issue. If the issue still occurs make a new issue and post your latest crash log.