If CST hasn't changed a lot between 2013 & 2014 versions, then it is straightforward. 

Step 1: Switch on the Local Coordinate Systems in the modeling tab.

Step 2:  In the drop down menu, choose Local Coordinate System properties. Shift the Local WCS to the 2D plane which contains your layer definition

Step 3: In the modeling tab, click on Import/Export Tab --> Export 2D --> Gerber (Single Layer)

Step 4: Layer in the plane of WCS should be highlighted, press enter. Finish by saving the exported file. 

 Hope this helps!

Regards

Dear Mr. Joshi Thanks for your prompt reply. I have done this way