Look into "Tagging for Effect", a process that combines two simple rules.
Creating an Aspect allows you one free Invoke of it, a Tag that costs and gives no Fate Points (see YS p.106).
Invoking for effect (see YS p.99) allows you to use an Aspect to declare a fact or circumstance that would be advantageous.
So Tagging "Cornered" for effect would allow, say, Murphy to use her free Tag to make the guy unable to escape...unless he gets rid of the Aspect.
That's pretty much how you do it.