I have started with a new company and wanted to contact past costumers and let them know where I am?

I would be very careful in doing this.

1. Not all past customers think this is professional.
2. If you signed a contract with your old company, please check and make sure that you didn't sign away this right.
3. No one can stop you from making a living at what you were trained to do. I don't know what business you were in however there may be only a limited number of customers in your area. I think this is a factor in your decision also.

I have taught, managed and been in sales for over 41 years. I believe that there are two basic skills needed; Inter personal skills and technical... technical (about your product or service) is always the easiest to learn. If you have the inter personal skills and have studied basic sales and have had success, you can sell anything. Always remember that buying is a very personal thing. People want to know that they made the right decision and they want to feel "warm and fuzzy" about that decision.

Sorry, more information than you needed?
Stringer