How do you learn about other apps on your devices? Attend MacNexus workshops on the first Saturday of the month. Attend Today at Apple sessions in a nearby store. Watch online videos. Read books about the apps.
Free Books from Apple:
Word processing and page layout (a la Microsoft Word and Adobe In-Design)
Presentations (a la Microsoft Powerpoint)
Spreadsheets and Budgeting (a la Microsoft Excel)
Use the Apple Store app to find Today at Apple activities for the week ahead or read about Product Skills sessions online.
YouTube hosts many tutorial videos, use the search option for "apple pages on ipad" for example to see a long list of Apple Pages on iPad tutorials. Modify your search to "apple keynote tutorials on ipad" and see the long list of Keynote tutorials. Change your search again to "apple numbers tutorials on ipad" to see the Numbers tutorials for iPad. Many of these tutorials will tell you what you need to know for iPhone as well. But just modify the search terms and swap out iPad for iPhone or Mac depending on the device you are using. Remember you want to match the tutorial to the version of your operating system and device.
Other free-access video sources exist for tutorials as well, but I found YouTube to be most helpful.
ScreenCasts Online created by Don McCallister is a monthly or annual subscription. There is an offer of 7-days free before you are charged. The video tutorials are downloadable. Consider the $8/month option if you are starting a project and want to brush up on the latest apps.
Video tutorials are a great way to learn. The option to PAUSE the presentation and try the techniques are very helpful. The REWIND feature too. Using a computer to view the tutorial while using your iPad or iPhone is also helpful.
Don't have a computer? You can go the your local public library and watch videos on their computers with audio headphones and use your iPad or iPhone with the techniques presented.
Or, if you are a solo learner, look at the templates for each app and dive right in.