To make the upload more reliable, you should zip up databases before uploading.
This reduces the upload time and reduces the risk of the file being corrupted.
Use Winzip or similar, or in Windows Explorer, right click the file and select "Send To -> Compressed (zipped) Folder", then upload the compressed file.
Upload times vary depending on your internet connection; however as a rough guide upload speeds should be 1-5 Mb/minute.
Browse for the required file.