If the Bible says we are only to follow God’s Commandments, how can the Church require its members to follow man-made precepts?

The precepts of the Church are not opposed to, nor are they outside of, the Commandments of God. They are within those Commandments and are intended to help keep the faithful within the Commandments.

There are basically six, listed in different ways in different books: (1) to attend Mass and to refrain from unnecessary work on Sundays and holy days; (2) to fast and abstain on appointed days; (3) to go to confession at least once a year; (4) to receive the Holy Eucharist at least once a year; (5) to contribute material support to the Church; and (6) not to marry within certain degrees of kindred. These precepts are intended to bind the faithful close to the Church and to God.