Q: how to check for apps that are running

Double click the home button.  They will appear on the bottom row, four at a time.  The list will keep going ... swipe right-to-left to see more.

Is this what you mean...

TASK BAR  iOS: Understanding multitasking

http://support.apple.com/kb/HT4211

More Info here  >  iPhone User Guide (For iOS 6 Software)

The directions seem straight forward but it doesn't work.

I follow these instructions but the "-" sign never comes up.  Once I release the icon, it just opens the ap.

If you want to close app, double tap the home button, then swipe upwards on the previews.

Sounds like you're on iOS7, which is different...

- From any Home Screen, double tap the home button to bring up the Recents List

- Swipe up on the app preview card

- Press the home button when done.

Thanks.  That worked.