Here are the steps which you need to take:
1 Log in to iCloud website with your Apple ID that you were using on your iPhone.
2 Go to Find My Phone option.
3 when you will click find my iPhone the present location of your Phone will appear Immediately on a map. but It will only happen if Internet is enabled on your iPhone otherwise you will not be able to locate it.
4 you can play sound on your iPhone by clicking the play sound option on right top. you can also enable the pass code on it so that the person who got your iPhone will not be able to go Inside your Phone. for this you need to pres on Lost mode option.
As I said above by using this method you will only be able to locate your Phone if the Phone and Internet on it are On otherwise you will not be able to find the location of your iPhone. I Will recommend all of you to use pass code on your Phone so that In case if you lost it somewhere your data remains safe from getting misused in wrong hands.