Dear sir,I am running an HR consultancy for software companies.I need self introduction letter about my concern to IT companies?

If you put the words introduction letter into a Google search, you are going to find lots of places where you will find sample etters of introduction that you could then tailor to be your own.

There are also links at the bottom of this page that you could click on to questions that have been similar to yours. You might want to click on them and see what the answers are.