From your account, click on Menus.
Select your live menu and click Change Menu.
Click the + sign here to add a section, and then change the name of the section by clicking on the Pen Symbol, writing the name of the section, and then clicking the check sign.
Then click on Create New Item.
Select Item Bundle.
Name your bundle, and fill in the required information of price, VAT rate, photo, etc. the same way you would for creating any new item. More information on how to do that HERE.
The only difference when creating a bundle will be in the Bundle Groups section.
Select Fixed as the Group Type if, for example, your bundle will come with the one choice of main.
Select Flexible as Group Type if, for example, orderers will get a choice of side or drink.
When you're finished, be sure to click on Save and Return twice, and then send your menu to review. If you're unclear about those steps, please find the tutorial HERE