Instead, you must log in to your iCloud account in a Web browser at www.icloud.com, click the iWork icon, click Keynote, and then drag your Keynote document into the browser window. After it uploads, the document will appear automatically in Keynote on your iOS device--but keep in mind that this process doesn't eliminate the compatibility issues I mentioned a moment ago.
If you don't use iCloud, another way to move the presentation onto your iPad is to open iTunes, select your iPad, click on the Apps tab, and select Keynote. Drag your presentation to the Keynote Documents list. Then open Keynote on your iPad, go to the Document Manager (if it's not already visible), tap the folder icon in the upper-right corner, and then tap your presentation. Or, if you want the convenience of cloud-based syncing without iCloud, a service called DropDAV ($5 per month) enables Keynote users to connect to Dropbox ( Macworld rated 4 out of 5 mice ) via WebDAV.
One note: If you've already created a presentation in PowerPoint, also take a look at SlideShark, a free iPad app for viewing and displaying PowerPoint presentations. It's not perfect, but it does a better job supporting PowerPoint documents than any other iPad app I've seen.
Use an external display
If your audience is very small--perhaps you're showing your portfolio to a potential client or giving your boss a quick demo--you could show your presentation on the iPad itself, albeit without the presenter notes. But you're more likely to prefer using a projector or other display.
Plug it in One way to do this is to plug a video adapter into your iPad's Dock connector, and then connect that to your display. You'll get the best results (and the highest resolution) using a display or projector with either the $39 Apple Digital AV Adapter (for displays with HDMI inputs) or the $29 Apple VGA Adapter (for displays with VGA inputs).