Although there is a built in theme editor in WordPress, I tend tuse Programmer’s notepad to make all but the quickest of edits to my WordPress files. Programmer’s Notepad is a free editor which is easy to use. It has the ability to use search, line counting, and word wrapping. To use Programmer’s Notepad, download the free version and Install. Then using Filezilla or another FTP program, before you begin editing any theme files, make a back-up of your complete website theme file directory by downloading the files to a specific back up folder on your computer. Then make a working file and copy a specific file that you would like to edit, to that file.
Open Programmers Notepad and select the file to edit. Make your changes and then FTP that file back into your “theme” file on your webhosting account. The old file will be overwritten with the new file. If you have made an error and get locked out of WordPress, go back to your backup folder and upload the original file through your FTP program, which will overwrite the file which is causing a fatal error, and you will be back in business and ready to figure out how to do it right. Happy Editing!