Without a compatible app on the iPad in which you can save, and edit these types of files, you can only email the files and read them as email attachments. So you will need an app that can save and edit the files.
Once you have apps that work with Word, Excel and PowerPoint - you can use File Sharing and transfer them via iTunes on your computer.
iOS: About file Sharing
You can use an app like DropBox in order to move the files from the computer to the iPad. You will need a free DropBox account to get started and will also need the DropBox app on the iPad.
DropBox for iPad.
You will also be able to transfer files using iCloud, if you setup an iCloud account.
Setting up iCloud on all of your devices.
And, as I mentioned at the beginning, you can email the documents as well.