Editing your website is done in a separate environment, the Craft control panel.
# Log on
Go to https://www.yourdomainname.com/admin (replace yourdomainname.com with your own domain name).
Enter your username or email address and password > Login
The URL to your Control Panel may differ. It depands on choices made during the installation of Craft. The exact URL can be obtained from the developer of your website. It is wise to change the default /admin login to a slightly less obvious URL.
During the Craft setup the developer can decide to only give the option to to log in with an email address. This results in not having the option to log in with either a username or an email address (as shown in the image).
# Sign out
In the upper right corner of the Control Panel, click the account icon > Sign out
# Lost password
Click Forgot your password? in case you don't remember your password.
Enter your username or email address and click Reset Password.
When the user exists in your Craft environment the system will send a special link to the corresponding email address in order to reset your password.