To edit information for yourself or others, you must be registered and signed in.
There is no "Sign-in/Register" link on the splash page, so instead choose any of the "Participating Fields" (they are all interconnected). It will open the splash page for that particular field. From this page, in the upper right corner, you can create an account or sign in to your existing account by clicking the "Sign-in/Register" button. This will open a dialog box to log in, with a link to "click here to create an account."
When you click on the Sign in/Register button in the upper right corner, a dialog box will appear in the center of the page, and the rest of the page will be dimmed.
If you have already created an account, enter the email address you used to create your account and the password you created into the fill-in fields in the dialog box, and press the Login button.
If you have forgotten your password, click the "Forgot password" link below the password field. This will take you to a new page, where you will be asked to enter your Login ID. This is not your email address, but rather the username that appears on any node you edit or links you create. A new password will then be emailed to the account you provided when you created your account.
When you first open the dialog box, it will prompt you to log in, as seen in the "How to Sign In" box above.
Above the fill-in lines for signing in, there will be a link you can click to register, where it says, "click here to create an account."
This will change the dialog box to the one seen on the left.
Follow the directions as indicated, and it will create an account for you. It is important to remember that this account will not create a linked node for you on the tree, but merely an account from which you can create nodes and links between them.