Make your text scroll horizontal across the page using this simple HTML, which loads fast. Here I use the <marquee> tag.
<font color="#000000"><marquee bgcolor="#FFFFFF" direction="left" loop="40" width="100%">How to create a marquee</marquee></font>
Add a new webpart to your site (Content Editor Webpart). Instead of clicking "Rich Text Editor" click "Source Editor". Copy and paste the text above into your source editor and edit it to your liking.
In the first <> are font color. You have to use the HTML color code for the color you wish the text to be. Here is a list of HTML color codes.
Next is the text background color. Right now it is FFFFFF which is white.
You can change the direction in which your text loops as well as the speed.
If you want to add your own message then simply change the text "how to create a marquee" to say what you want it say. There are tons of customization options you can use, these are only a few. Google is your best friend!