A large portion of church giving comes via cash donations placed either in the church offering plate or a donation box without an envelope or another way to identify the donor. This article covers how to record anonymous cash donations.
In ChurchTrac, every donation has to be assigned to an individual. So create a fake person on the People screen to whom you will assign all anonymous donations.
On your People Screen, create an organization and name it something like Cash Offering or Anonymous Donor.
Once you have created the "person" to assign your cash offerings to, navigate to the Giving Screen and add a contribution with the "person" selected as the designated giver.