The easiest way to do this is usually to click on the cloud icon in the bottom right hand corner by the clock on the laptop, sign in with your usual school email address/password and then turn the Backup function on - this automatically uploads any files in the Desktop, Documents and Pictures folders to the Cloud, and importantly, also backs up any new files created in those folders too automatically. If you have any files not in those folders that need backing up then would suggest moving them to one of these folders, probably the Documents folder