Simply replace the unfilled areas such as "__" and "_[date]_" with your information.
My name is _[Name]_ and I am the _[position]_ of the _[Club/Association]_. We are an organization that is dedicated to _[club purpose]_. We provide _[services]_ and _[additional services]_ to _[recipients of service]_.
_[Referring Party]_ gave me your name as someone who may be interested in our group. I understand that you _[qualification]_. I would like to invite you to join our _[club/association]_. I have taken the liberty of enclosing our information pamphlets. Please take some time to look over them. Also, I would like to invite you to attend our meeting on _[date]_ at _[time]_ located at _[location]_. This will give you an opportunity to meet other members and decide if you would like to join.
Let me know if I can answer any of your questions.