To mask an object

1. Select an object that you want to mask. (The object you will paste into the second object.)

2. On the Standard toolbar, click Copy to copy your the object to the Clipboard.

3. Select an object that you want to use as a mask outline. (The object you will be pasting the first object into.)

4. On the Effects menu, point to Masking and then click Paste Inside. A blue edit border appears around the mask-outline object.

5. Position the outline of the object to be pasted, then double-click. A copy of the first object is pasted inside the second one.