If he prays Witr as eleven rak'ahs, there is only one manner for him to do so: he concludes with salām after every two rak'ahs, then prays one rak'ah as Witr. (1)

The minimum complete form is three rak'ahs with two salāms: in the first he recites Sūrat al-Aʿlā, in the second Sūrat al-Kāfirūn, and in the third Sūrat al-Ikhlāṣ. ...........

His statement, “The minimum complete form is three rak'ahs with two salāms,” means that the minimum complete form of Witr is to pray two rak'ahs and conclude with salām, then perform one rak'ah and conclude with salām. (2)

It is permissible to perform them with one salām, but with one tashahhud rather than two; for if he were to perform two tashahhuds, it would resemble the Maghrib prayer. The Prophet ﷺ forbade making it resemble the Maghrib prayer. (3)

His statement, “In the first he recites Sūrat al-Aʿlā, in the second Sūrat al-Kāfirūn, and in the third Sūrat al-Ikhlāṣ,” means that, in the first rak'ah of the three, he recites Sūrat al-Aʿlā in its entirety; in the second, Sūrat al-Kāfirūn; and in the third, Sūrat al-Ikhlāṣ. (4)

This is after al-Fātiḥah. The author did not mention it because it is well known: there is no prayer for one who does not recite the Opening of the Book.