If you have forgotten your password (and have not loked it out by too many incorrect attempts) you can go through the password reset process using the forgotten password link.

This opens the password reset form.  Fill in your username and then use the link at the bottom and this will set your current password to expired and email you a link to set up a new one.  Using the same form again this time type and confirm your new password.  Any currently applied password policies will apply.