I followed these directions
"To change the “Sales Message Goes Here” or “Tagline Here” text to say what you want open the includes/languages/english/header.php file in your text editor. Find the following line of code:

define('HEADER_SALES_TEXT', 'Tagline Here');>>

Replace the tagline text with your own text, making sure that the single quote marks are not left out.

Save the edited file to includes/languages/english/custom/header.php and upload it to your server.

NB: By default the text “Sales Message Goes Here” is located in includes/languages/english/classic/header.php define('HEADER_SALES_TEXT', 'Sales Message Goes Here');"

I am using Crimson Editor. When I go to save the document as includes/languages/english/custom/header.php, it tells me this is an invalid file name.