Follow the steps below to upload a file/folder to your webspace using Webfiles.
Webfiles provides an interface where you can upload files to your webspace. The Webfiles interface is limited, most notably, by restricting uploads to one file at a time. For multiple uploads, FTP or Secure FTP is recommended.
Log in to the 1&1 Control Panel using your Customer ID OR domain name and your password.
If you have only one package, you will land on the Administration page. If you have more than one package, select the package in question to reach its Administration page.
Click the Webfiles link from the Hosting panel.
Click the Launch button to launch WebFiles.
Select Transfer > Upload.
Select Transfer > Upload
The maximum file size for upload is 100MB. Here you can use the Select button to select a file from your computer to upload. Using the folder list below, you can choose where to upload the file to your webspace.
Once finished, click the OK button to begin the upload.
Select a file and a location, then click OK
For additional information, you may want to reference: