If she just broke up with her boyfriend, she might be emotional. You have the choice to make, use this time to either give her space or if you feel it is necessary, comfort her. This'll show you're even more by her side. After she's over her past boyfriend (and make sure she's not caught up in someone else) begin to slowly make it noticeable that you like her to the point of being boyfriend/girlfriend. When the timing is right, and in a collective sort of way, ask her out.
The Lone Warrior UnForGivenSR 0X