Need a little help here please Flash gamess expertise!

i am making a slider image puzzle games my problem is i read all article about AS in “collision” but nothings works, imagine you have two square (square1,square2) what i want to happen is the square1 must not pass through with the square2 it is like walls to each other ether i can use the drag and drop or the cursor key up, down, right, left…

i know everyone of you already played the puzzle slider games could somebody help me out with my problem please! an FLA… of yours that i can download can be very helpful on me. even a simple 2 square…

thanks in advance guyz!!! GOD BLESS