I could understand my parents speaking italian but I never spoke it. How can I learn to speak italian?

There are many ways to learn a language... depends on how you like to learn. E.g. you can take classes (local community college, Italian cultural center), you can hire a private tutor or you can go to Italy or all of the above in a mix. You can try on your own as well... however at least at the beginning you need somebody to validate your understanding (in language contrary to math there is no right or wrong answer or there are multiple answers).

good luck. It worth it though as Italian is a truly beautiful language.

I just got back from work. It takes me almost an hour to drive to work and almost an hour to get home. I listen to Italian CDs all the way to work and all the way home. It's like having a traveling language lab.

For speaking it's very easy even if you don't have someone to speak to especially if you say you understand Italian. Just get a book or magazine or anything in Italian and read out loud.
Get Italian books that have dialogs and play both parts. Many Italian books have CDs that go right along with the book. I know I've got a lot of Italian books that have CDs that go along with them.

Per esempio: For example:

Signorina Corona: Buon giorno, signor Rossi.

Signor Rossi: Buon giorno, signorina Corona. Come sta?

Signorina Corona: Bene, grazie. E Lei?

Signor Rossi: Molto bene. Sono contento di riverderLa. I'm happy to see you again.

Signorina Corona: Anch'io. (ahn-KEY-oh) Me too.

Signor Rossi: Quanto tempo sta in Italia? How long will you staying in Italy?

Signorina Corona: Non sto molto: solamente una settimna. Signor Rossi, Le presento la signora Shandra. I'm not staying long: only one week. Mr. Rossi, let me introduce Mrs. Shandra to you.

Signor Rossi: Molto piacere. Niced to meet you.

Signora Shandra: Al contrario. Il piacere è tutto mio. On the contrary. The pleasure is all mine.

Read this over and over and let me know when you're ready for the next dialogo. (dee-AH-lo-go)