SSH
Use a SSH client (e.g. PuTTY, FireFTP, etc)
Give it the device IP address, select SSH, port 22.
These are the default user account details:
Username: Administrator
Password: p@ssw0rd (this will likely may have been changed by you when ssetting up the device)
If it won't connect try re-booting the device (we had to after it had done an update to get SSH to work)
Windows PowerShell Session
The Power Shell for IoT Core page
Feel free to comment if you can add help to this page or point out issues and solutions you have found. I do not provide support on this site, if you need help with a problem head over to stack overflow.