At the moment it looks like your panel is long and narrow. It really depends what you want to do with it. Is it going to be a throw? If so, you might just want to add a border all around. But if you want to make it wider, I would suggest cutting the smaller squares from top and bottom, sewing them together into a single strip and adding them to one side. You might have to flesh out the main part of the panel with sashing to get the size right.
You can also Google 'quilt panel ideas' and then press 'images' at the top of the page. That should give you lots of ideas.