If you've got some flash content that you'd like to insert into your site, it's easy. Just upload your flash file (which will have an '.swf' extension) by first clicking 'choose file', then clicking browse, finding the file on your computer, and then upload.
Just wait for the file to upload, which may take a few moments. When your file has been successfully uploaded, this dialog box will appear. Just click close.
Choose the file by left clicking the file, and selecting 'choose'. Click 'add' when you're done.
If your particular flash file has specific requirements on quality or minimum flash player version, enter them in the fields. 99% of people just leave these as the defaults .