Catholics follow the Ten Commandments because Christ, Himself, followed them and because He told others to follow them (Matthew 19:16-19). We also follow them because they were given to us by God. In the book of Exodus we read how God himself gave these commandments to the Israelites through the help of Moses. However there is more to following the Ten Commandments than just because 'God told us to.'
We obey God's commands because He loves us! Because God loves us and loves us perfectly we can always trust His word. Also, because God created us we can trust that He always knows what is best for us.