Um, do you mean ISO image? If so dvd decrypter can burn this on its own.
If you mean an .IFO file then you will need to make sure you have the other files, such as .BUP's and .VOBS. IFO files are just tiny information files for DVDs with chapter, menu and title information and dont actually hold any video content.
Use nero or another burning suite. Make a new DVD Video compilation. Drag ALL the files that dvd decrypter ripped into the VIDEO_TS folder. Burn.
If the files are too big you need to reduce (compress) them. DVDSHRINK does a great job and is among the easiest to use programs in existance.