I'm creating my first custom Outlook Form. How can I put the voting buttons (Approve and Reject) in the body of this form (instead of on the menu and toolbar)?

In form design mode, switch to the (Actions) tab and you'll see a custom action for each voting button that you created (Approve and Reject, in your example).

Figure 1, page 6, shows a set of actions for ordering sandwiches. Double-click an action to see its properties, which Figure 2, page 6, shows. You can turn off the menu and toolbar commands by clearing the Show action on check box. Back on the (Actions) tab, notice the name of the actions. Use these names in the code for the command buttons on your form. For example, you can use the code

Sub cmdOrderRoastBeef_Click()
    Item.Actions("Roast  beef").Execute
End Sub

for a command button named cmd OrderRoastBeef to run the Roast beef action and produce the same result as clicking a Roast beef voting button. Note, however, that this code will trigger a user prompt if the user is running Outlook 2002 or using Outlook 2000 or Outlook 98 with the Outlook Email Security Update. To avoid the prompt, the Exchange administrator must deploy the components for managing security settings and allow custom actions to run programmatically without a prompt.