Login
Once you have properly set up your account you can login to Salesforce at any time while you have your license. The link to the login screen is https://afcs.my.salesforce.com/
Bookmarking the page while you are in the midst of your search is highly recommended.
Note: Going directly to Salesforce.com login will not let you log in. You will get an error. It is important to always use the above link.