On the OneDrive website, sign in with your account, and then browse to the location where you want to add the files.
Select Upload.
Select the files you want to upload, and then select Open.
Direct Link for more information: https://support.office.com/en-us/article/upload-and-save-files-and-folders-to-onedrive-for-business-a1397e56-61ec-4ed2-9dac-727bf8ac3357