In WordPress adding tags is very simple
Adding tags to your WordPress posts will help you organize your blog’s content.
Tags will also help your visitors find their way around your site more easily. It increase more website visitors to your blog.
To add tags to a new post login to your blog’s admin area Posts -> Add New. When you write your new post, you can add a tag to it by typing the tag word in the Tags field on the right and clicking the Add button. You can add as many tags as you want.