This is the very basics of using elastic time in Pro Tools. This techinque is for moving real audio beats around like MIDI, for instance if you have a loop but some of the upbeats are clashing and thus need to be retimed to a more forgiving down beat (think when your beats arn't in sync when you DJ).
This article assumes you understand the basic of using Pro Tools.
Scenario: two tracks of drums are clashing and so some beats of loop two need to be moved so as to stay in time.
Walk through: first elastic time needs to be enabled, it helps to have both enabled as you will see the transient (start of the wave form) marker on both tracks.
To do this make your track in the edit window large enough so you can clearly read and see all the info the track contains beside meters on the left side of where all the recorded tracks are.
Now see the picture of a timer? it looks like a triangle with a stick out the top of it. Click on it and you will see a menu with several elastic audio algorithms on it. Choose rythmic as the algorithm as your working with beats not basslines (you would choose monophonic in that case, or for guitar or piano chords you would choose polyphonic)
What happens now is that Pro Tools analysis the wave form for transients, the progress of which can be seen by switching to analysis view (near elestic time theis a menu that says "waveform" on it click that and choose analysis)
though this is optional.
Now that its done analysing you can switch to warp view. Do this by clicking on the menu icon with "wave form" written on it (as in the optional part) and select "warp" view.
You should now see the pictures of the waveforms have have lines on them marking just before where the wave form gets bigger. These are warp markers, this is where you are moving your beats from.
Double click on the marker BEFORE the beat you want to move. This marker is your first anchor point, the second is the marker AFTER the beat your moving. You should now see a blue line witha triangle on the bottom on either side of the beat you want to move
Double click and drag the marker thats on the beat you want to move. Any time you click and drag on the marker your moving it to a new position, so drag it to somewhere loop one has a beat too. if you swithced both the views to elastic view earlier like recommended at the start of the article make sure the lines match up on screen and your beats will play exactly at the same time.