It is very easy to do in practice but kind of difficult to describe with just words, how to make round corners for a square box! I am sure there are many ways to do it. Let me see...the one that comes to my mind would be...umm...okay.
Make a square selection on a new layer. Use the rectangle tool. Fill it up with the color of your choice. Now take the eliptical tool and make an eliptical selection carefully so that the edge of the eliptic touches the square's corner in just the way you would want the square to curve. Carefully select everything else of the square with the rectangle selection tool except for the small rectangle part where the eliptical selection touches the corner. Invert the whole selection. That would leave just the tiny curved part selected. Delete it! Now you can repeat the process for every other corners of the square.
I know it is a horrible description of how to do something in photoshop. But I don't know how to say it better. Play with the selection tools. Those are the keys.
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I want to make a square that has round corners. I hope I can make it understand you. Like you see many buttons on the web. That is not all sharp corner. I want something like that. Instead of sharp corner I want a curvy corner. I have been thinking of how to do it easily. But I can't seem to figure it out. 
Anyone can help me out please?
