you can try from any one of these::
http://www.devwebpro.com/25-rounded-corners-techniques-with-css/
you can try from any one of these::
http://www.devwebpro.com/25-rounded-corners-techniques-with-css/
I've been wrestling with rounded corners in this way today. I'm using GIF's which have the corners in the colour of the background. Because these are GIF's the corners could be transparent, but I'd rather not worry about what's 'behind'. But in your situation a GIF would be better than a JPG(is this what you are doing?), as transparency is supported, or a PNG if you don't need to support old browsers. Then you can put the background colour in the style for the DIV is you want too.
HTH
My personal favorite technique is this one: even more rounded corners. Look at the demo page: http://www.schillmania.com/projects/dialog2/. It does exactly what you want.
Plus, unlike other techniques, you don't have to cut up your background image.
Here is the good example to create rounded corners with custom images
http://www.templatespoint.com/blog/2010/10/expandable-rounded-corner-box/