How to get onsite tcs

It's sad that you are not aware of this after 6 years.

First of all, the project you are in should have onsite openings or you should get into projects which has onsite openings. You should have the skills that the project requires and your project management should believe in your capabilities. If it’s all in place then approach your manager and express your interest they will definitely consider you and will initiate Visa for you.