If you're new to web development and search engine optimization, you may find this tool useful for ensuring your meta tags are correctly formed. The tool has two fields -- Keywords and Description:
Keywords: Enter a short list of keywords and terms related to your site. The terms can be separated by a comma, but a delimiter is not required.

Description: Enter a brief description of your site and what it offers. This is sometimes used by search engines as a website’s “snippet” for search results.

About Meta Tags: At one point meta tags were considered a relatively important factor by search engines. AltaVista and other older search engines used them to help determine a site’s theme as well as relevance to a given term. This is no longer the case; search engines now rely on much more advanced techniques to do this. That said, meta tags still have some life left in them; they are sometimes used as the snippet of a site's content in search engine result pages by Google, and possibly other search engines. It's also possible they still have a little influence with some search engines in determining a site’s content.