Login to your Gmail account.
Once the page has fully loaded, look on teh left side of the page.
You’d see a sidebar.
In the lower part of the sidebar, is an input box that says: “Search Chat and sms.”

In that type the number, and ENTER. A box will pop up. Name your contact and select its country.
THATS IT.
Now you can chat with him normally
NOTE THAT SMS REQUIRES CREDIT. you ONLY HAVE 50. AFTER THAT U’L HAVE TO BUY SOME MORE!