Cannot find alpha channel

Hi. I am using Blender 2.68 and can’t find alpha channel/slider. I have seen this tutorial

Could you help me please?

The Alpha slider is located under the Material context, not the Texture context. It is located under the Transparency rollout panel. You must activate the checkbox to use it.

Made that, but couldn’t see the slider. I am interested in lowering the transparency on a ramp. I could not find the A slider, that sets the transparency for each ramp color.

Got it. It was under RGB, when color selecting.