What kinds of gaps am I looking for?

You look for capability gaps in the people, tools and other resources used, and you look for operational or organizational gaps which all feed into problem statements. For example, if the current state looks like X, and the future or goal state looks like Y, then the Gap Analysis assesses the gaps between the current and goal states. Having identified the gaps, you can prioritize them, quantify the work efforts related to them, determine if solving them will require "pulling levers" related to people, processes, or technology, and start to define the next steps.