I downloaded bootstrap framework using this link available on codeplex.
I have created empty sharepoint project in visual studio 2013. Then manually added bootstrap related files in Layout folder. See my project files in visual studio below
Now i went to my page and selected site settings. Then i selected Look and feel >Master page. But i cannot see bootstrap.master. How can i see that in site settings. I am using sharepoint 2013
Update1
My element.xml is as below
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
<Module Name="MasterPage" List="116" Url="_catalogs/masterpage">
<File Path="MasterPage\acme.master" Url="acme.master" />
<File Path="MasterPage\bootstrap3.master" Url="bootstrap3.master" />
</Module>
My module1's element.xml is as below
<?xml version="1.0" encoding="utf-8"?>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
<Module Name="Module1">
<File Path="Module1\Mycustom.css" Url="Mycustom.css" />
</Module>
</Elements>