Learn Finnish: Maalautamme seinät. - We are having the walls painted.

The base verb is maalata (to paint). First, find the present tense stem, which is maalaa-. To express having someone else do the action, we add the curative suffix -uttaa to get the infinitive maalauttaa. Finally, we conjugate it for "we" by adding the personal ending -mme, resulting in maalautamme.

Why is it maalauttaa and not maalaauttaa? What happened to the long A?

When you attach the -uttaa suffix to a verb stem that ends in a long vowel, like maalaa-, Finnish phonetics step in to prevent an awkward three-vowel cluster. The long vowel is shortened, making it maalauttaa.

Why is the object seinät in the nominative plural rather than the partitive?

This is a total object. Using the nominative plural (the -t ending) shows that the action is intended to be completed fully: we are having all of the specified walls painted. If we were only having some of the walls painted, or if the action was ongoing, we would use the partitive plural seiniä.

If we wanted to specify who is actually doing the painting, how would we add that to the sentence?

With curative verbs like maalauttaa, the person commissioned to perform the action is put in the adessive case (ending in -lla or -llä). For example, to say "We are having the painter paint the walls", you would say Maalautamme seinät maalarilla.