Installing SQL Server 2008

SQL Server Installation 

Click on "Installation".

Installation

Click on "New SQL Server stand-alone installation or add features to an existing installation".
 
Add Features to An Existing Installation

Click on the "OK" button.

OK Button

Click on the "Install" button that will install the setup support files.

install setup support files

Click on "Next" to continue.
 
Next to Continue

Specify the edition as "Enterprise Evaluation" in the "Specify a free edition" box and click on the "Next" button.

free edition as enterprise evaluation

Check the check box “I Accept the License Terms” and click on the "Next" button:

Accept the License Terms

Click on the "Select All" button then click on the "Next" button.
Select All button 

Choose the “Default Instance” then click on the "Next" button.

Default Instance

Just click on the "Next" button.



Set the Account Name as indicated in the diagram then click on the "Next" button.

Set Account Name

Select “Mixed Mode Authentication” then provide the password for the sa account then click on the “Add Current User” button then click on the "Next" button.
 
Mixed Mode Authentication
 
Click on the “Add Current User” button then click on the "Next" button.
 
add current user

Just click on the "Next" Button.
 
Add User

Just click on the "Next" Button.

Next

Just click on the "Next" Button.
 
Next Button click

Click on the "Install" button .