Search for file type you want to add. Here i want to add html file so i entered html and search for it by clicking magnifying glass icon as shown in above screen shot.

As you can see search results give me file types that contains html in it. Now as you can see in the screen shot above search icon is replaced with red stop icon. This stop icon represent the Cancel Search button. Click on that button to return to the main screen if you don't satisfy with the results. Here i want to add html file type to new menu so i will select the html file type from the list and click Add To New Menu button as shown in the above screen shot. You will presented with below dialog.

Here Empty File represents 0 byte file if you choose this then when you create this type of file it contains no data. Here it will work because html files don't require formating information from the start but file types like Microsoft Word Documents(.docx),Microsoft Excel Documents(.xlsx) and some others require some inner formating to validate it as a valid file. If you want to add these type of file use Predefined Template File. Just create empty file from appropriate application like word, excel or any other then browse for it and click OK. When you create new file that has been added with Predefined Template File option, file will contain all the information in the template you gave in creation process. Here i want to have new html template when i create this file so i will select that option and browse for my template.html file after doing that i will click on the OK button. If your file type doesn't appear in new menu than refresh your window twice.

As you can see from above dialog when i create new html file using new menu then all the data from the template is still there.

To remove file type from the new menu select it from right list and click Remove From New Button as shown in above screen shot.