The BNI Forum is not an open group. It is intended that the membership should be by invitation, recomendation and request. If you have received an email invitation directly from the site or another member just follow the link in the email and it will bypass the need for an invitation code.
If you do not have a code but would like to engage with the other BNI members here just post a help request for an invitation code. Include your full name, business name and your BNI membership status, if you are a member of a chapter just give us the chapter name!