我需要更改或编码哪些文件才能将wordpress项目重定向到新的locaction

Question

I have created a new wordpress project in my laptop using MAMP, I was watching a tutorial on how to change the project to a subfolder on Lynda in order to have many pages trough MAMP, so first I went to the Wordpress Addres (URL) and change to localhost/thenewdfolder (that I previously have created) and did the same in the field Site Addres URL, in the settings of the dashboard of the page. Then I moved the entire files to the new folder or subfolder, I refreshed the page but appeared the "Internal Server Error". What I would like to do is try to find the .php file or files and with a coding editor give the new paths and make the necessary changes, but I see on internet and looks like trying to go to the moon. So is that possible? should I to start again the project? thanks for any help...