First, enter your mind map's root branch – just press on it and start typing.

There are now three methods of expanding on your mindmap from here:
 
1. Double left-click into the mind map’s background and start typing – this creates a new box. Now drag and drop to link the boxes and create branches.

2. Select on the main idea or another box – it should now be outlined in blue. Now press Insert on your keyboard to create a new sub-branch. You can also create multiple branches on your current level by hitting the Enter key.

3. Select a branch and use the Branch or Sub-branch buttons on the Home ribbon of the toolbar.