Filezilla is a GUI program for both SSH File Transfer or SFTP. Install using your distribution's software manager or download from filezilla-project.org. Lauch the program, choose File > Site Manager > New Site. Configure SFTP connection to gauss:

Protocol: SFTP - SSH File Transfer Protocol
Host: math.dartmouth.edu
Logon Type: Ask for password
User: your username on gauss

Click OK to save configuration or Connect to save and connect at once.