God’s will is what is revealed to us in the Torah. The Torah that was given to us at Mt. Sinai some 3,300 years ago was the communication of God to us, explaining the meaning of all existence, the purpose of our individual life and the nature of our national destiny. When one studies the Torah it is as if God is speaking and communicating with the person.
According to Judaism doing God's will is accomplished by observing the commandments, by being good to those around them and by refining one’s character traits. These actions will bring a person closer to God and ultimately build a place in the World to Come.
Of course, it's a lot easier to write that than say it! It is a life-long task that we each have to try and draw closer to God, each one of us in our own way but all of us in the way that God wants us to do it.