Application validation allows you to ensure that your form application is correctly configured before you publish your site. It checks for missing information in field properties and form properties. This is especially helpful when accepting money through your form.
To add more field types, just drag the appropriate Field Type onto your form. Each Field Type will be added to the bottom. Need to move a field up or down within your form, see Move Field within Form for more information.
Other Handy Information
Add Form Application to web page within site