Simply replace the unfilled areas such as "__" and "_[date]_" with your information.
To All Staff:
Please allow me to take this opportunity to introduce myself to all of you. My name is [name], your new [type of position]. It is a pleasure to have joined [name of organization]. I consider myself fortunate to have been given this opportunity to join an organization with such a fine reputation for its [quality products/services/etc.].
This [type] position offers new and exciting challenges to me, all of which I am looking forward to. Prior to coming to [name of organization], my background entailed [briefly describe the field you worked in]. The last position I held was, [type of position] with [name of organization]. Now, I look forward to this new position where my responsibilities will include [briefly describe position] and I'm quite anxious to get started with these new challenges.
I can see already that this is a fine group of people I will be working with. I'm looking forward to having an opportunity of chatting with each of you over the next while. Glad to be on board!