The "Meta Keywords" is part of the HTML family of programming tags that many people believe help with your SEO efforts. It doesn't matter if you knowing how to program it or where it belongs inside web pages because it's worthless for SEO. In fact the only thing a "Meta keyword" is good for is to confuse your rival jewelry store.
It wasn't always this way. Meta Keywords weren't always worthless. In the mid 90s they were used as the main way for search engines to analyze your website. But unscrupulous people decided to stuff hundreds or repetitive keywords into the Meta Keywords setting making their website the most popular.
And when they dropped in popularity they would simply add another hundred permutations of their keyword into this meta tag field.
Around 1997 all search engines stopped using this meta tag for website analysis. This is publicly documented in the directions and how-to guides from each search engine. Yet to this day more than 13 years later, people still believe that "Meta Keywords" are important.
You're smarter than your competitor. If you have a local competitor that is always copying you I would then recommend putting 8 to 10 keywords into the Meta Keywords to confuse them.
Use words vaguely related to the content on each page, but DO NOT use the same words you also have in your page headline. In case you have forgotten, your page headline would be the words you designate as your Heading 1.