Create a New Module in AX 7 / D365 Finance and Operations

Step 1: Create a Menu Item

1. Add a new Item to your Project .  Under Dynamics 365 Items go to User Interface.  Select Display Menu Item and give appropriate name to it.
2. Now open the Designer and Set the Properties of the Menu Item. Set the label Name for the Menu Item, Specify the Object to Run under Object.
3. Refer this Menu Item under the Properties of Menu.

Step 2: Create a Menu

1. Add a new Item to your Project Under Dynamics 365 Items go to User Interface Select Menu and give appropriate name to it.
2. Now open the Designer and Set the Properties of the Menu. Set the Label Name for the Menu under Appearance and Menu Item name under Data.

Step 3: Link the Menu Item under Menu

1. Open the Menu  Drag and drop the Display Menu Item from the Solution Explorer to the Menu.

Step 4: Display the New Module

1. Open the AOT and expand the Main Menu. Right click and click on Create Extension.
2. You will be able to see the MainMenu.Extension in your solution Explorer. Rename it and open in Designer.
3. Right click on the MainMenu.Extension and add new Menu Reference.
4. Rename the Reference Menu and set its Properties.
5. Set the Menu Name to the Menu Created in Step 2

Compile your Project
You can see your Module in the Main Menu.