How to convert the master-page to the HTML. I've made changes to CSS (which i want to use) and i found the only way to do so by adding it to the HTML conversion of the master page. I'm new to the Sharepoint so there might be a different way to do so, which i didn't found. Thank you for any help.
First of all, you need to Take a look at this link first: http://msdn.microsoft.com/en-us/library/office/jj822370(v=office.15).aspx#Understand
This is necessary to start with SharePoint master page.
As per your question I am unable to get your point but as far as I understood, you need to change the same on HTML page first, after that change will automatically reflected on master page file. You don't need to change directly on master page file when you have the html file.
If you find this as solution, mark this as answer. :)