AE is certainly the right software for this task. What issues are you having?
Thanks for responding - After i crop out the face from the photo still - how do i move it the movie and have that extracted face follow the face of the individual in the movie?
Start here: Basic AE. Unfortunately there is no replace face button in After Effects. You are trying to do a composite and there are several steps that you must follow.
AE is not a software that you can just open up and use without training.
The procedure that is best suited to your task depends entirely on the shot you are trying to track and the final effect you want to achieve. At a minimum you'll have to learn about Motion Tracking, using nulls and parenting as well as the basic animation skills in the first link.
When you have a handle on the basics then type Motion Tracking in the search help field at the top right corner of AE and look at the training materials available from the Adobe Community. Do the same for Parenting and Nulls.
At the most basic level you would track something like the left and right eye of the face you are trying to replace using Motion Tracking, then apply the tracking info to a null, then parent the face to the null and adjust the position and scale.
At a higher level you would track the face in Mocha and use some advanced corner pin tracking and rotoscope techniques along with Stabilize Motion to replace the face. You may even want to go as far as creating a displacement map, using Freeform Pro and doing a bunch of other things to replace the face. It all depends on what you want to do.