1. Control Panel -> E-mail Forms -> Mail forms management
2. Click Create new mail form
3. Fill in the fields. You may provide either one e-mail address for receiving letters from site users or several. Then click Create form
4. You can adjust fields of the e-mail form as you like (edit existing fields, create new fields, change their order, make them required or not) by means of Fields constructor.
5. After you have adjusted the fields you must Rebuild form template.
6. If you haven't deleted the default Contact Us page from the Page Editor (CP -> Page Editor -> Pages Management) then it will appear on the menu automatically. Otherwise copy the code of the created E-mail form (e.g. $MFORM_1$), go to Page Editor -> Add new page and paste this code.