How to write a self introduction letter asa a new colleague to all staff on first day at work?

At least here in the US, I have never heard of this or seen it done and I have been in business for well over 30 years.

Is this a custom where you are from, have you spoken to your senior staff person as to their tradition, perhaps gotten copies of the last few done to use as an example

As Chuck said, this is not your responsibility, at least in the US. Its up to your manager to introduce you to your colleagues. And I prefer the personal approach here. Your manager should take you around and introduce you personally.

Hi, tari428!

If you are required to write something, then you might want to consider posting a draft here without putting any contact information in it.

I'm sure that there would be those of us who would be willing to review it and make suggestions to you as to how you might make improvements to it.

Thanks!

I think it's better if someone else introduces you in person. If the company has a newsletter or something like that, they might customarily print a blurb about the new people and you might be asked for some information, but keep it short and sweet.

I've never heard of doing a letter, and probably wouldn't do it unless your boss asked you to do so. People will get to know you in time - no need to do a letter.