How to create custom header in magento 2.3.3

I am creating a store in Magento 2.3.3.I have created a custom header but its not showing in frontend.

I have done the following steps for creating the custom header:

1. Created a file named customheader.phtml in magento_theme folder inside my theme folder i-e myvendor/mytheme/Magento_Theme/html/customheader.phtml

2. I have added the following code in my dafault.xml file

After Adding the above code I have executed the following commands;

php bin/magento setup:upgrade && php bin/magento setup:static-content:deploy -f && php bin/magento cache:flush

I have searched the web but no luck.

I think you already do great implement but just forgot to clear everything in root/generated/code folder