To change your password, go to your user profile homepage, scroll down to Security and Privacy, and type your old as well as your new password. To make sure you are not mistyping the password and locking yourself out, you are asked for your new password twice.
The new password is effective immediately.
If your organization is using a centralized password scheme, e.g. LDAP or SAML, you will not be able to change your password here. In this case, please ask your IT Helpdesk or the Stages Administrator on how to change your password.