Sushi attemped.

So I tried to make sushi today and I made some interesting discovery.  For the sea weed you will see lines that is where you will cut to make the size of each sushi the same, it is not where you roll.  So to cut it evenly is to make sure that the open part is face down.  The only part I can not figure out is to make sure how to make sure the sushi does not open up?  Anyone one knows please leave a comment.  Thank you.