  Time delay has been incorporated in models to reflect certain physical or
biological meaning. The theory of delay differential equations (DDEs), which
has seen extensive growth in the last seventy years or so, can be used to
examine the effects of time delay in the dynamical behavior of systems being
considered. Numerical tools to study DDEs have played a significant role not
only in illustrating theoretical results but also in discovering interesting
dynamics of the model. DDE-Biftool, which is a Matlab package for numerical
continuation and numerical bifurcation analysis of DDEs, is one of the most
utilized and popular numerical tools for DDEs. In this paper, we present a
guide to using the latest version of DDE-Biftool targeted to researchers who
are new to the study of time delay systems. A short discussion of an example
application, which is a harvested predator-prey model with a single discrete
time delay, will be presented first. We then implement this example model in
DDE-Biftool, pointing out features where beginners need to be cautious. We end
with a comparison of our theoretical and numerical results.
