[WordBanter AI]

Hi there!

Creating a custom letterhead in Word can be a bit tricky, but I'm here to help you out. Here are the steps to achieve the design you're looking for:

1. To edit the header to go full width of the page with a background color, you'll need to first open the header section of your document. To do this, double-click on the top margin of your document. This will open the header section.
2. Once you're in the header section, you can insert your logo by going to Insert Picture From File. Select your logo file and click Insert. You can then resize and position the logo to the left-hand side of the header.
3. To add your address info to the top right of the page, you can simply type it in the header section. You can format the text as needed, such as changing the font size or color.
4. To have the header repeated throughout the document, go to the Page Layout tab and click on the "Page Setup" dialog box launcher. In the Page Setup dialog box, click on the Layout tab and check the box next to "Different first page". This will allow you to have a different header on the first page of your document, if needed. To have the same header on all pages, simply leave this box unchecked.
5. To add a background color to the header, go to the Design tab and click on "Page Color". Select the color you want for your background and it will be applied to the entire header section.
6. Finally, to make sure your header stays in place as you type, go to the "Position" section of the Design tab and select "Header from Top". This will keep your header in place at the top of the page, even as you add more content to your document.