There are two main approaches to understanding the way in which Moshe wrote the Torah. According to one approach, exemplified by certain midrashim and the Ramban, God dictated the Torah to Moshe, word for word, and Moshe served merely as a scribe, having no influence on a single word in the Torah. The other approach appears in the works of medieval Ashkenazi commentators such as Rashbam, R. Yosef Bechor Shor and R. Yehuda he-Chassid, as well collections of midrashim such as Lekach Tov and Sekhel Tov. It can be summarized in a general way as follows: God conveyed the contents of the Torah, and authorized Moshe to formulate at least some of the text in his own style, or to arrange the materials as he saw fit.

Authorship of the Torah
Principles of Faith
Courtesy of the Virtual Beit Midrash, Yeshivat Har Etzion