You can upload a file from the web browser to all the files on the switch, except default-config, which is read-only. Select the file to upload, select the destination file on the target, then click Upload Configuration.
If the destination is running-config, the file will be applied to the switch configuration. This can be done in two ways:
If the file system is full (that is, contains the three system files mentioned above plus two other files), it is not possible to create new files. An existing file must be overwritten or another file deleted first.