Add copy to post tag pages

Does anyone know of a plugin / widget that allows you to add copy to post tag pages? e.g. I have several videos of ‘snowboarding tricks’ to which I have added the tag ‘snowboard tricks’. I want this tag page to be searchable in search engines for the keyword ‘snowboard tricks’ and want to add some extra copy to the page. Is this possible? I’ve searched high and low for a plugin to no avail.

Thanks

loulouxx88