Once you login for the first time, you will want to explore, but the first thing you should do is to connect ClassLink to your cohoes.org Google Account. The tutorial video will show you how to that. Once complete, you will be able to use the "Sign in with Google button" on the ClassLink login page. As another benefit, once you connect your Google account, when you login to the Chromebook and open Chrome, the ClassLink dashboard will be your homescreen.
In the future, if you ever change your cohoes.org network password, you will need to reconnect your Google Account using your new password.