I created a New Page from Master in SharePoint Designer using a custom master page. I can open the page and edit it freely in Designer, but when I open the page in the browser, it treats it like a webpart page, meaning I cannot add anything unless I have a webpart zone. I would rather not use webpart zones, because I would like my users to be able to move things around later. Is there some way to make SharePoint treat my new pages more like wikipages? Or is there a setting I missed?
I am not clear from your question, although seems like you are asking about creating/editing new page in Sharepoint using SharePoint designer. Follow the below link, hope it will help