How to upload the file even after doing the post back.

Question

I have Rad Cloud upload control on the page, I want to upload files to Amazon S3 server. I selected 10 files.and I2 files get uploaded .in middle of remaining uploading I did post back.the remaining files are not uploaded to the S3 server.My doubt is If the user selects big files like 1gb etc.how can he wait for that much time.after selecting the files, he is able to do other work on the page until the files are uploaded.please help me....