Well, there are two ways. The way I prefer and has been reliable is to open the stock_attributes.sql with a text editor, and highlight all the code and select copy. Be sure you highlighted all the code and not just part. Then go into the Admin section and goto Tool -> Install SQL Patches. Then paste the information that you just copied into the big form area on the screen. It is very important that you don't type anything extra here. Next press 'send' to have the sql statements processed. You will get a message that lets you know if the process was successful or failed, and you go from there.
The other way is to go to Admin->Tools -> Install SQL Patches. There is a browse button where you could browse for the file on your hard drive, select the file, then click upload. I've heard that this method is not as reliable for some reason so I don't use it.
Now there is a recommendation that you back up you database before you run any sql statements into it. Even if you don't backup your database everytime, at least do it occasionally. There is this download called
MySQL Backup for Zen Cart that you may want to download to make this easier. I personally use the backup from PHPMyAdmin from my webhost provider.[/SIZE]