A primary click and a secondary click. You can change the default button settings with a program called mouse in the control panel folder in My Computer. You can also get to the control panel by clicking the Start button then pointing to the Settings item. Use this for selecting, dragging, double clicking and re-sizing. The pointer changes into two opposite pointing arrows.
Theses are the resize arrows.
When they are present, left-click and drag the object to a different size. Next left-click on one of the items in the short menu that is displayed.