How do you put a picture inside a square...

Hey all, I'm new around here and have a question. Back in first semester of school, my Photoshop teacher taught our class some pretty cool stuff. I don't remember even the half of it. Anyway, here's the question.

For a web page, website, whatever you want to call it, this is what I'm trying to figure out. I want to be able to make a shape of anything, like a square, and inside that square add a picture of something. I want to be able to move that picture anywhere inside that square, without it coming outside, showing only a portion of the picture. Any of you familiar with what I'm asking? I've looked at a grip of tutorials, but so far I've failed in finding the right one. Help would be much appreciated.

I'd say you'd need to add a layer mask to it.

hi!!!!

u need 2 do a simple trick.... just follow the steps....

1. create a shape in layer 1.
2. open a picture in layer 2.

3. remember to keep the layer in fllowing orders.
i. background layer, ii. layer2 and then layer 1(shape layer should be at the back).

4. press alt and click in between layer 2 and layer 1, the shape of the mouse will change.... (i put the attachment of the view of layer and mouse)

5. or if u can't work with no. 4 point then go to layer menu and select "group with previous option"....

6. u should get ur result now...

bye for now.. enjoy photoshop...