Graph Theory is a branch of mathematics that concerns itself with the study of graphs. Network neuroscience uses graph theoretical concepts to study brain networks. In this lecture, I describe the advent of Graph Theory and Network Science, before introducing various basic graph theoretical measures and discussing their application to Neuroimaging Data. The second half of the seminar includes hands-on coding exercises. The students learn how functional connectivity networks can be characterised using Graph Theory and how they can make inferences about the network properties using Null Networks.