I don’t know what to do my MacBook Air have firmware lock and I don’t know how to get it off

Are you the original purchaser or did you buy it used?

If you're the original purchaser you will have to take the machine and the original proof of purchase to Apple or an authorized service provider.

If you are not the original purchaser, you may as well sell it as scrap or just recycle it.

There is no way past that.