For example: If your site was about Stamp Collecting, you would use the following tags;
<meta name= "description" content="everything you wanted to know about stamp collecting.">
<meta name= "keywords" content="stamps, stamp collecting, stamp history, prices, stamps for sale.">
You have a meta description tag first = general interest about the name of your site, then meta keywords = individual words that relate to what the site is about.
To help you more (don't pay for the creation of meta tags) use this free site to create the tags for you; click here; simply copy and paste them into your html code AFTER the <head> tag.
Good luck.... Neil.