There is, I believe, a 20MB limit on uploaded scenarios. There may be some things you can do to reduce the size of your scenario. First, start by remove any and all sound and image files currently in your 'sounds' and 'images' folders of your project folder that are not being used (you may not find you have any to remove -- but so be it). Next, make sure you use the 'jpg' (or 'jpeg') format for images used in the backgrounds of any of your worlds (they use less storage space than other formats). Also, if you can reduce the size of any of your sound files either by cutting their length or using a different file format, that would help. Another way to reduce the size of the project is to reduce the size of any or all of your worlds and proportionally reducing the size of the images used in those worlds.