You can use the parameter feature in QuickTest to enhance 
your test or component by parameterizing the values that it 
uses. A parameter is a variable that is assigned a value 
from an external data source or generator. 

You can parameterize values in steps and checkpoints in 
your test or component. You can also parameterize the 
values of action parameters. 

If you wish to parameterize the same value in several steps 
in your test or component, you may want to consider using 
the Data Driver rather than adding parameters manually. 

There are four types of parameters: 

Test, action or component parameters enable you to use 
values passed from your test or component, or values from 
other actions in your test. 
 In order to use a value within a specific action, you must 
pass the value down through the action hierarchy of your 
test to the required action. You can then use that 
parameter value to parameterize a step in your test or 
component. 

For example, suppose that you want to parameterize a step 
in Action3 using a value that is passed into your test from 
the external application that runs (calls) your test. You 
can pass the value from the test level to Action1 (a top-
level action) to Action3 (a child action of Action1), and 
then parameterize the required step using this Action input 
parameter value (that was passed through from the external 
application). 

 Data Table parameters enable you to create a data-driven 
test (or action) that runs several times using the data you 
supply. In each repetition, or iteration, QuickTest uses a 
different value from the Data Table.
For example, suppose your application or Web site includes 
a feature that enables users to search for contact 
information from a membership database. When the user 
enters a member's name, the member's contact information is 
displayed, together with a button labelled View <MemName>'s 
Picture, where <MemName> is the name of the member. You can 
parameterize the name property of the button so that during 
each iteration of the run session, QuickTest can identify 
the different picture buttons. 

Environment variable parameters enable you to use variable 
values from other sources during the run session. These may 
be values you supply, or values that QuickTest generates 
for you based on conditions and options you choose.
For example, you can have QuickTest read all the values for 
filling in a Web form from an external file, or you can use 
one of QuickTest's built-in environment variables to insert 
current information about the machine running the test or 
component. 

Random number parameters enable you to insert random 
numbers as values in your test or component. For example, 
to check how your application handles small and large 
ticket orders, you can have QuickTest generate a random 
number and insert it in a number of tickets edit field.

Thank you  Saikrishna Reddy. I know there are 4 types but I
used only variable through Data Table. 
I will try other 3 in the script. Thanks a lot once again.

A parameter is avariable that is assigned a value from an 
external data source or generator.You can parameterize 
values in steps and checkpoints in your test or component. 
You can also parameterize the values of action parameters.
There are four types of parameters:

1. Test, action or component parameters
2. Data Table parameters
3. Environment variable parameters
4. Random number parameters