Use the right & left arrow buttons to find a card on this level that needs a Child Card on the next level down. While in that card, click on the "Create Child" button. This will create a Child Card attached to this card. You will end up viewing the new Child Card, with the cursor in the "Self Name" field, ready for entry of the new card's name. Note that the Parent Card's name is shown in the top field.
Enter the card's name in the "Self Name" field, and any data in the "Data" field.
Use the "Create Peer" button to create more cards if they are to be attached to the same parent.
Repeat this step to go to the next level if appropriate, or navigate around the database with the arrow buttons, and add Child and Peer cards, as appropriate.