You can change the dimensions of an object by scaling it, that is, enlarge or reduce the size horizontally (X-axis), vertically (Y-axis) or from both axes.
How to scale objects with the Scale tool
    1. Select the objects you want to scale with the Selection tool.
    2. Click the Scale buttton on the control panel of the Selection tool.
    3. On the reference point locator, click a white square to set a reference point from where to scale. A crosshair symbol is displayed in the defined position.
    4. Drag the cursor to scale the object. (To scale the object proportionally, hold down the Shift key while dragging.)
        scale
        –OR–
        Enter a scaling percentage. (Click the Link symbol so that both values are the same.)
        –OR–
        Enter the horizontal and/or vertical dimensions. (The corresponding percentual scale is calculated automatically.)