At some point in your game you may want the player to choose something from a list of possibilities - to do this, create the menu by selecting "Menus" from the tree menu and add a menu. The menu name is internal to your game, and is the name you must use in the script that calls this menu.
You can specify an information prompt that will appear at the top of the menu. This is to provide instructions to the player as to what this menu is for. For example, "Choose your weapon:".
Then add choices by clicking "Add", entering the text for the choice and then specifying what script will be run when this is selected from the menu.
When something is selected from the menu, the menu disappears, the relevant script for the selection is run and the game continues.
To show a menu, use the "Show a menu" script command (in the "Run script" category) at the point you want the menu to be displayed.