Cannot get iPhoto files off of external HD onto new Macbook Pro

I cannot transfer my iPhoto files from my external hard drive onto my new Macbook Pro. Using Migration Assistant is out of the question because the old operating system is so antiquated it does not effectively find the files. I was instructed by Apple Support to put the files from the old computer onto an external HD and then move them manually onto my new hard drive. However, when I tried to open the iPhoto pictures from the external HD, it would not allow me to select them. I realize that iPhoto does not exist anymore, which is probably causing the confusing. Is there any "workaround" for this? Thanks!