Mandar, you can add Century Gothic but you need to download the various format font files. If you go to fonts.google.com you can search for Century Gothic and you will be offered the option to purchase it. It is owned by monotype. If you follow this route, download the font file/s and select webfont in WX5 to embed it in your project.

A simpler (and free way) to have an extremely similar font is to select google fonts in WX5 and select Didact (didact gothic regular)