When creating a SIP Trunk you will be prompted for a password. This is required to be a secure mix of letters and numbers. You will need to keep the password secure, however in the event that you do lose it then it is always possible to reset the password at a later date. Your connected device will need to be set with the new password if this happens.
Once the trunk has been created it will appear in a list of SIP Trunks on your account. You can then manage a variety of settings to the right of each of the displayed trunks.