Converting a PAL DVD to NTSC format implies that you bought the DVD with the content and also you are allowed to copy the DVD.
Insert the DVD you want to edit into the DVD-ROM and click
Explore while you are in My Computer then copy the content to a location of your choice and browse VIDEO_TS folder. Inside you will have different files and you need to look after IFO files like
Download IfoEdit from our website and save it where you want and perform installation using the setup you downloaded. Start the application and drag each IFO file you find in the folder and where you see PAL double click and a window will open and all you need to do is to select NTSC, click OK and save the file. Perform the same operation with all IFO files. After you finish modifying all files use a burning software, start a new project and choose DVD-VIDEO format, and drag VIDEOTS & AUDIOTS folders to the root of the DVD and burn it using speed of your choice which is supported by the DVD disc.