In your Zen Cart Admin ...
You have a menubar ... one of the titles reads: Tools
Under Tools there is a menu choice for: Insert SQL Patches
This is a section of code made to allow you to issue a command that changes the data in the database ...
You need to change all of the products_price settings in the products table of your database ...
To do this, you want to make a backup of your database ...
This can be done via phpMyAdmin that should be located in your web site control panel ...
Or, by getting the Backup MySQL add-on in the Downloads located at the top of your screen ...
The command that I gave you to paste into the Insert SQL Patch page:
UPDATE products SET products_price=9.50 where products_price=9.00;
Is designed to change all Products that currently have the products_price of 9.00 to the products_price of 9.50 all in one command ...
Then in the Tools ... Store Manager ... is an option to globally update the products_price_sorter ... so that the pricing works and sorts as if you had manually made all of these changes ... this is accomplished running the second setting that I gave you:
Update ALL Products Price Sorter
to be able to sort by displayed prices: Update
I don't know what HTML has to do with any of this, but I think that is just a confusion on terms ...
You have a database and that database contains the tables with the records of information about each product ...
You want to update all of those records related to existing products with 9.00 prices in one fell swoop vs one by one ...
That is what these two command run through your Zen Cart Admin are meant to do ...