Hello Lynch508,
please update your Internet Browser and try it again or try another browser. I use Google Chrome Version 45.0.2454.85 m, it is the newest Version of Chrome.
What yo need to do is go to your .minecraft folder and click on saves then right click on the specific world you want to upload then right click, then click sent to, then compressed zip folder and then click on the new save below the original save then upload that one.