That's a 2-step process.
1. Do all backups you want and need to an external hard disk in a format that is suitable for step 2, that is: packed into a small number of compressed files. Details depend on what backup program(s) you use.
2. Copy those files to the online data storage (on some webservice like Dropbox or Microsofts Skydrive) from the external disk. Details depend on the service you choose.
how to backup whole of mycomputercand D drivefoldersin an online data storage device