Getting over obstacles in your path is what turns a run into a freerun.
As a beginner, you should be starting off with small objects, just a couple of feet high at most. Try some simple vaults over low railings and benches, and work your way up from there.
As you take on more and more obstacles, you’ll learn to spot more opportunities and more challenging routes, but don’t take on too much, too soon.
Accidents do happen, but are easily avoided if you know your limits.