Your Referee Development Officer should have given you a list of contact details for Referee Secretaries for all grass roots Leagues in your County.
Depending on referee coverage in your area, you may find it much easier to get assigned to youth games, which is arguably a better idea than charging straight into Open Age. In my limited experience, some RefSecs are miles better then others, so it's pot luck when deciding which one to contact first. You need to get setup on the Whole Game System ASAP, so you can record your games there and report and cautions/dismissals
Again, your RDO or course tutor should have given you a form to record your five games on
I don't think the RDOs or tutors do enough to help trainees get assigned to games and complete the qualification process