Missing Canvas in Unity

Please help me out …i am new to unity .i want to create menu using canvas. but there is missing Game UI sub menu to create canvas inside unity …

You can add a canvas component through the Add Component button on your GameObject of choice. A Canvas is just a component like anything else.

If you are missing the UI menu you are probably running Unity 4.5. The canvas is only available in the 4.6 beta. Download here

Its potentially still a couple of months away before its final release. However now that Unity 5 is in beta it may be pushed along in more of a hurry. Would be a bit odd to release 5.0 before 4.6. There have been indications from unity staff members that that would be unlikely, but not impossible.