1- Click on the Insert tab.
2- Click on the Header.
3- Choose “Edit Header”.
4- Click on the Design tab.
5- In the Insert part, you can select “Picture” or “Online Picture” options to insert your desired picture.
6- Find your desired picture and click on Insert key.
7- Click on the Format tab.
Here you can modify your picture properties, for instance in the size part you can change the size of your picture as you need.
8- Click on the Design tab.
9- Click on the “Close Header and Footer”.