i film my sons sports on my phone. I want to be able to record on my iphone and when i get home sign into my ipad and backup to the ipad? but idk need to put the data from ipad on to th eiphone. any suggestions?

Apple doesn't offer an option to backup an iPhone to an iPad. See the following for backup options: How to back up your iPhone, iPad, and iPod touch - Apple Support

If you only want to copy a video from the iPhone to the iPad, one option is AirDrop. See: How to use AirDrop on your iPhone or iPad - Apple Support

Other options (email, messages) are also described in Share photos and videos on iPhone - Apple Support

Assuming that both your iPad and iPhone are signed-in to iCloud with the same AppleID, have you considered simply enabling iCloud Photos on both devices?

Settings > [Your Name / AppleID] > iCloud > Photos > Sync this iPad | iPhone - set to ON

Once enabled, your photos/videos will be saved to iCloud - and will be immediately available to both iPhone and iPad without any additional steps.

Set up and use iCloud Photos - Apple Support