Trying to get an update in the app store. I put in my password and it says I need a code as well. What code? Where do I get the code? I can't get in. Please help.

I'm totally frustrated. I'm trying to get my updates from the Apple Store. When I put in my password it says I need a verification code. It doesn't tell me where to get that code. Then it want's me to check forget password. I've changed my password and I get the same request for verification code. Where do I get that code? I'm stuck. Please help. I'm 76 and not that computer savvy. Thanks. I am using a Macbook Air