Position your cursor in the section in question.
Click View > Header and Footer, then position the cursor in the Header.
Click View > Toolbars > Drawing, then click the Insert Wordart button from
the Drawing toolbar.
Select the first cell in the Select a WordArt Style box, then click OK.
In the Text box, type a T, set the size to 96 points, then click OK to
insert the image into your header.
Click the Format WordArt toolbar button, select the Colors and Lines tab,
then select a light gray color for the Line Color.
Select the Layout tab, click Behind Text, then click OK.
Close all the toolbars you opened, including the Header and Footer toolbar.
You may need to repeat these steps for other headers in your section. You
can simply copy and paste the WordArt into other headers as well.
Bear
PS: If this is actually what you're trying to do, I'm taking the rest of the
day off.