iCloud new AppleID, how do I get it on my cellphone?

That is Activation Lock Find My iPhone Activation Lock

You will need to know the password. Apple can help with that: If you forgot your Apple ID password

If the old ID is an earlier version of the ID you are trying to change it to, do the following:

Make sure you are signed into iMessage and FaceTime with your current ID. If they are signed into the old ID, go to Settings>Messages>Send & Receive and Settings>FaceTime, tap the ID, sign out, then sign back in with your current ID.

Then temporarily recreate the old ID by going to https://appleid.apple.com, click Manage my Apple ID and sign in with your current iCloud ID. Click edit next to the primary email account, change it back to your old email address and save the change. (You should not have to verify the old email account so it doesn’t matter if you no longer have access to it.) Now go to Settings>iCloud, turn off Find My iDevice and enter your current password when prompted (even though it prompts you for the password for your old ID). Then save any photo stream photos that you wish to keep to your camera roll (unless using iCloud Photo Library). When finished goThen go to Settings>iCloud, tap Sign Out (or Delete Account if you are not running iOS 8) and choose Delete from My iDevice when prompted (your iCloud data will still be in iCloud). Next, go back to https://appleid.apple.com and change your primary email address back to the way it was. Now you can go to Settings>iCloud and sign back in with your current iCloud ID and password (your data will download back to your device).