How do I make a Gui Text on an object?

I am trying to make a text show on a wall, but it is not working! Can you help?

You might try using a Text Mesh Component to get the effect you want.

You could create a light cookie for the text, and then project the text onto the wall (I'm assuming you want something similar to what was featured prominently in Splinter Cell Conviction). They used a light/projector with the words as the cookie for the light, which then projected the words onto the walls/floors/etc.

Have a look at Text Mesh component (How do I make a Gui Text on an object? - Questions & Answers - Unity Discussions)

It looks like you need to render a text to a texture, so you need the "render to texture" function which is disabled on Unity FREE version.

Solution unless you need that text changing: make a texture of that text and apply it to the wall on UV2.