Similar to the previous post on How to Setup WordPress on iPhone, here are the steps to setup WordPress client on an iPad:
Go to App Store and search for WordPress by Automattic. Once you find it, just tap on the INSTALL button.
Once installed, open the app and make the selection that’s applicable to you. The options are pretty straight forward. If you have a blog either self-hosted or with WordPress.com, you just need to tap on the corresponding Blog option. Or if you don’t have one, you can open a new account with WordPress.com. As an example for this site, it is a self-hosted blog, so the first option, + Add Self-Hosted Blog should be selected.
Enter your blog URL, username and password on the Add Blog screen. Turn on Geotagging as necessary.
Tap Save button on the upper right-hand corner and all your postings will be listed on the next screen.
In the same way to the setup on iPhone, if you have multiple blogs, you can add more blogs by going to Settings, tap on Add a Blog, and repeat the whole process above.