Set Line spacing to Double, then click OK.. Set your header. In an MLA format, the header gives your last name and a page number on each page. Click View on the main menu, then Header and Footer from the menu that drops down.The header section will appear on your document inside a dotted-line gray square. Type your last name and a single space.et Line spacing to Double, then click OK.. Set your header. In an MLA format, the header gives your last name and a page number on each page. Click View on the main menu, then Header and Footer from the menu that drops down.