Music Information Retrieval is an evolving field, which also includes research on music pattern discovery. This thesis describes the implementation of an online annotation tool, which allows researchers to more easily conduct pattern annotation experiments and removes the need for digitization of hand-written annotation. The tool is used in an experiment in collaboration with the Department of Musicology at the Faculty of Arts (University of Ljubljana) and the Academy of Music (University of Ljubljana) as well as the Department of Music Pedagogy at the Faculty of Education (University of Maribor). The result of the experiment is an annotated database of musical patterns. We present an analysis of the gathered user data and make comparisons between patterns annotated by students of the aforementioned groups.