To make use of the full power of your iPad, you'll need to install applications, they can be downloaded directly from the App Store using the Apple App Store application that comes pe-installed on your iPad, or you can download from your PC with iTunes and then transfer them to your iPad.
For the second method you'll need to have:
iTunes installed on your PC
Have an iTunes account
Then follow these steps:
Open iTunes on your PC
Click on "iTunes Store" in the left column, then click the tab "App Store" and then "iPad".
Use the search box located on the upper right corner to find the application you are looking for or do a search by category.
Download the application
Connect your iPad to your PC and iTunes will automatically sync with your device, thus automatically installing software on your iPad.
The software's icon appears on the home screen.
If after the sync process the application is not installed, do the following:
Under iTunes> Go to Devices >select your, then click on "Applications", check the box next to the application you want to install on the iPad and click "Apply"