how do i transfer apps from a iphone 5 to a iphone6

Transfer content from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support

Basically you b ack the old one up, then when you set up the new one you restore it from the backup you just made of the old one, making it a near clone.

It would be much easier to simply download them again on your new phone; however, you can also use the backup you made in iTunes of your old phone and use the restore function.

If one of the phones is not yours, you can't copy/transfer them.