Look for the Keynote app icon on your Home Screen and Tap on it to open the App. It´s the white lectern on a light blue background.

On the next screen you can see your current presentations and you can create a new presentaiton by tapping on the blank slide icon with a + in the middle.

Now you can choose between different themes. Those themes are slide templates that facilitate the creation of your presentation.

Keynote now has created your first presentation and automatically adds a first title slide. You can now enter a title by double tapping on indicated text field.

This is how the slide with a title should look like.

Hint:

If you want you could also add a subtitle to your slide by double tapping the text field under your title.

Tap on the + – button at the left lower corner to choose the template with a title, bullet points and a placeholder picture on the right.

To insert a picture tap on the +button at the right lower corner of the placeholder picture. 

Now you can access your camera roll and select a picture of your choice.

Now you can add a title to your slide as you did with before and insert your bullet points by double tapping on the text field and pressing enter after each bullet point.

After inserting your content the slide should look similar to the sample image above.

Now you can add a final picture slide by tapping again on the + Button and choosing the template with a big picture covering the whole slide.

After that replace the placeholder picture and add a picture of your choice.

You can change the order of your slides very easily. Tap and hold on a slide preview on the left side until it lifts up and seems to stick on your finger. Then you can move it up to the second position and release your finger. 

Tap on the play button in the toolbar on the top to start your presentation.

You can tap on a slide to move to the next slide.

Hint:
If you swipe from the right to the left you can go one slide backt.