If you already have an activated Champlain account, go to https://champlain.instructure.com and enter your Champlain user name and password. If you still need assistance, click "Request assistance" on this page.
If you already have a Canvas account, you can try resetting your password here: https://champlain.instructure.com/login/canvas. If you still need assistance, click "Request assistance" on this page.