In the GardenWeb search box at the top of the page type "pruning oleanders". There's a small topic on it. That phrase also gets scads of hits on google.

Thanks for your response. I saw the topic on pruning oleanders, but when I read it, it was about bushes. I have found a lot on the web related to bushes, but not on how to prune trees. I don't know if they are pruned differently.

You want a "ball on a stick" kind of oleander?

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Start by making the "stick" ... pick the most vertical shoot it has. Prune off all the side branches and force it into an upright with a single stem. You may have to stake it for a while.

Shorten the branches at the top to encourage them to branch out.

Keep pruning off any side buds below the spot you want the ball part, and keep the ball pruned.

For a multi-branched oleander "tree", pick several thick branches and prune off the side shoots for a few feet above the ground. As the tree grows, keep pruning up the stem until you have a smallish tree.

Oleanders aren't trees; they're bushes. You can form them into small trees with judicious pruning. The first time I saw them as something more than a mess was in Ajo, AZ where they're planted around the town square. Beautiful. The link below has a link to all you'd ever need to know about oleanders.

Here is a link that might be useful: oleander 'trees'

Okay, here's another possibility, The International Oleander Society below

Here is a link that might be useful: www.oleander.org

Thank you everyone for all of your suggestions. I really appreciated them. I want my oleanders to look like the ball form in the photo above. I definitely need to do some pruning of my trees, but now that it is Spring and there are buds on the branches, I guess I have to wait until Fall.