how do I add the apps from my iphone to my ipad?

Apps cannot be transferred between iOS/iPadOS devices. Instead, assuming that the Apps are both compatible with the device and are still available (i.e., have not been withdrawn or retired from the App Store) you simply download them again from the App Store. In most cases, if signed-in with the same AppleID, you’ll not need to pay for the Apps for subsequent download on another device.

How did you set up your iPad? If its your first iPad, you could have set it up from the backup of your iPhone and any apps which are also iPad compatible would be transferred to the new iPad. If you didn't restore the iPad from an iPhone backup open the App Store app on your iPad. Tap the little circle at the top right hand corner with your picture. Tap Purchased, Tap My Purchases. Tap Not on this iPad. Any app which you own, which can be downloaded to your iPad, will appear with a cloud icon next to it. Tap the cloud next to all apps you want and they will download to your iPad.

Note: Your iPad and iPhone must be on the same Apple ID.