I have an old Mac Book air form 2006. How do I get Mac OS 10.13 or higher.??

I'm assuming you mean you have an old white MacBook from 2006.

As noted above, the MacBook Air was released in 2008.

Of course, it could be an old iBook G4. Those were sold into 2006.

Either way, You're not going to get anywhere near 10.13 on that machine.

There was no MacBook Air until 2008.