To apply a texture to a shape, choose "Textures" from the Fill menu on the Home tab.
There are lots of built-in textures to choose from organized by style and type: Bark, Brick, Fabric, Flowers, Granite, Grass, Metal, Paving Stones, Rock, Roof, Stone, Tile, Stone, Water, Cabinetry, Wood Flooring, Carpet, and Paper.
To apply a texture, click on it and hit OK.
Edit the Texture
Click the "Edit" button if you want to fine-tune how your texture looks.
Scaling the Texture
Change the scale of the texture to increase or reduce the size of the repeating pattern.
You can also specify where the pattern starts in the shape. The default alignment is "Top Left" of the shape. To change the alignment, select the radio button by "Align the texture with the Top Left of the shape". This will allow you to bring up a drop-down of other alignment options.
Depending on the pattern, this may or may not make a big difference. It usually results in a bigger visible change in irregular patterns.