I regularly use the plugin “All in One SEO” for my themes. You can manage this by going to “Settings” and then “All in One SEO.” Click the top box that says “enable” and then fill out the top three boxes that are currently empty.
Home Title: This is the title of your site.
Home Description: This is the description of your site that will show up in the search engines.
Home Keywords: Put keywords in here that you think people will search for to find your site. These words should be comma separated and you do not need to repeat them. For example if your keywords are: Sherman Plumbing, Sherman Electrician you would just put “Sherman, Plumbing, Electrician.”
Scroll to the bottom and click “update options.”