How to lock phone automaticlly?

I feel like I should know this, but I can't seem to figure it out. I apologize in advance if its a stupid question.
How do I get my Sprint 9930 to lock automaticlly? I bought a new slim case from the Sprint store and the clip doesn't have a magnet. So it doesn't lock after a give time. The screen goes out, but I can hold in a key and dial someone. Very annoying and embaresing.
I know I can hit the top center buttom. But is there a setting that will make it happen when the screens goes out?
Any suggestions or help please.

Some options ....

Set a password. And use the password lock.
Install and use a third party application.
Press the lock button manually.

Options--> Security --> Password. You set it to lock after idle.

Or

Hold down the "A" key.

Or

Top lock key

Didn't think of third party app.

Patterlock by tafasa is awesome too! Unlock with swipe of the finger.

Posted from my CrackBerry at wapforums.crackberry.com

i just push my K key and it locks

Use speedlock, you can slide to unlock phone, dont need to use the top button. $0.99 is great deal!

Originally Posted by blueyestm

i just push my K key and it locks

That's what I do. You (OP) have to turn off dialing from home screen so you can use the shortcuts. I never use the top button.

Just hold the "A" key for about a second until the screen shuts off. Regardless of the universal search of the application short cuts.

Going back to the other replies, yes you can hit "K," but if you don't want to use a password and just want to set the phone in stand by without using the top button then "A" is the way to go without additional software.

Originally Posted by vinaconex

Use speedlock, you can slide to unlock phone, dont need to use the top button. $0.99 is great deal!

+1 on SpeedLock. My fav lock app by far!

PatternLock by Tafasa works great for me. Tons of settings. Can be set to lock immediately when screen turns off, or wait certain amount of time. Customizable background and many more.

Speedlock for me