Hello there Kayrakaye,
It sounds like the Pinch and Zoom checkbox might be unchecked in the System Preferences.
Check this out from the article Mac Basics: Set your preferences found here: http://support.apple.com/kb/ht2490.
Customize your trackpad
Trackpad preferences lets you control the clicking, scrolling, zooming, and gestures of your trackpad.
- Open System Preferences.
- Choose View > Trackpad, or click Trackpad.
- To change your tracking speed and click settings, click the Point & Click tab. Then, move the Tracking slider to adjust how fast the arrow moves across your screen; move it left to slow it down, or right to speed it up. You can also enable secondary-click by selecting the "Secondary click" checkbox. You can then click using two fingers to secondary-click. The secondary-click can be used to display shortcut (contextual) menus for an application.
- To change your scroll and zoom settings, click the Scroll & Zoom tab. You can enable and disable scroll and zoom gestures.
All the best,