If you need to add SharePoint Field Controls or any other SharePoint Controls such as search box,navigation etc in your custom layout, you can use the Snippet gallery to Copy the required field Control code and paste it into your custom Layout's html file.In this post however we will only look at an example of Creating a Custom Page Layout and using it to Create a Custom Page. If you want to edit the page layout and add a code from Snippet gallery, see the upcoming post on 'Add Snippets in Layout Page using Snippet gallery in SharePoint 2013'.
Before you begin make sure that you have Publishing Feature enabled on your site and you see "Deisgn Manager" under Look and feel.
Lets look at the detailed steps -
1. Navigate to Site Settings -> Design Manager (under look and feel).
2. Next in Design Manager select "6. Edit Page Layouts" and then "Create a page layout"
3. Now Create a Custom Page layout using the Article Page Content type.
4. When the Layout is Created, it gets available in "Edit Page Layouts" list and the "Master Page gallery" of the site.The Layout Page will be in Drafts mode until you publish it as a major version.
5. Next Edit the New Layout Page and save the Changes.In SharePoint 2013 for every Layout page two files - .aspx and html are created by default.
For making Changes to the Custom Layout, you need to download the html file (see above - Custom page Layout.html) of your layout page and make Changes to it.The modified html file is then saved back to the MasterPage Page gallery where the corresponding .aspx file gets updated automatically.
For editing, see the detailed post on How to add Snippets from Snippet Gallery in Layout Pages in SharePoint 2013
6. Once you have updated and saved the Layout page, you need to Publish the Layout page as a major version to make it available in Layouts list.
7. Finally, Create a new Page with your Custom Layout.
Navigate to Site Content in Site Settings and then Open the "Pages" gallery.
Click on the 'FILES' tab and select Page.
Finally Create a new Page with your Custom Layout.
To know more about Editing the Layout Pages and how to add a SharePoint Field Control in it, take a look at Our next post on 'Add Snippets in Layout Page using Snippet gallery'.
Also see - Add an Html Master Page to SharePoint 2013 using Design Manager