Use the SFTP Create Directory action to create a directory on the remote server.
Specify the new directory name. Make sure the directory is a full path (specified from the user's home directory). The SFTP protocol doesn't have the concept of a "current directory" like FTP does. Creating a directory tree (ie. more than one directory specified doesn't exist, is server dependent - if not supported by the server you will likely get a "permission denied" error).
Optionally fail the action if the directory to create already exists on the server.
Specify the permissions that the new directory should have.