Nick here from Shopify.
Shopify actually has a very helpful guide on how to verify your website with any and all third party services which you can see by clicking here. It goes through all the steps and shows you what to add and where. Don't hesitate to reach out should you have any other questions about this or anything else.
All the best, Nick
Theres a button that says verification with google search consale
(this is if you already verified for google merchant center )
you place the code in the theme.liquid
right below the <head> tab
Log in to shopify store
click on right coloum that says online store
click on themes
click on actions drop down arrow
click on edit code
find the file that says theme.liquid
paste the code bing tells you right under <head> (not </head> but <head>
wait patiencely for 5 minutes
try to verify again
if this doesnt work contact bing support
hope this helps
i remember when i first started learning this stuff wish these forums had a good detailed answer
heres me giving back
DONT GIVE UP i went from 0 dollars a day to 25k a day
it is possible!