The usual form fields used in a page are the name and email fields, but you can always add an additional field for other information like phone number, company name or address etc, but to make it work (capture the information inputted in the field) you will need to sync it with your autoresponder.
To add a field, click on Add New from your Page Editor, select Form and drag the type of form field to your page.
When adding a form field to your page, you need to add the same type of field in your autoresponder form and sync the Name of Field of 10 Minute Funnels and your autoresponder so that the autoresponder will be able to collect the information placed in the additional form field. The steps for syncing the Name of Field and adding a form field in the autoresponder varies depending on the autoresponder. Click below for specific tutorials: