I previously asked this Question: How to create WSP Package of a SharePoint 2010 site without VS 2010 (with SP Designer)?.

But didn't get a proper answer. I am developing a SharePoint 2010 website. I am not the admin for central administration. I am just one Site's administrator in the farm. I just changed the CSS of master pages and added some sub sites, blogs. How can I create a WSP solution with Visual Studio 2012 or SP Designer 2010?

I want to have all the web parts, all the custom master pages, all the modified css, all the libraries and sub-sites that I created. How can I accomplish it?