Hello! Are you going for rounded corners like you have in the image? In that case, you want to delete all the little border scoops (which should be marked out in the code as such, the little white circles that let me cheat for the inward-corner effect). They're the ones that look like:
Just delete all that stuff - and then, within your table tag (like where you've got bgcolor and width), add:
From there, you can mess around with the value to get more or less of a curve. Higher values will increase the curve, lower values will get you closer to the square corner.