help creating sniper scope

[Nate Vander plas]

What exactly are you having trouble with? Seems fairly straight-forward to me, but if you have no idea how to go about it I suggest finding some basic training for After Effects. Here are some steps to get you started:
First find some images online to help you know what it really looks like
Create a circular mask on a black solid (add feather if you want)
Create crosshairs by adding the grid effect and increasing the width and height until you have two lines intersecting
Put footage below this layer

[Majorasshole]

make it in photoshop or illustrator and import it in with an alpha channel.
I suppose you could gang up a few layers in a comp with a circle and some lines etc, but the photoshop/illustrator method is much easier and will look much better.