how can i use this new apple id to replace the old one

While you can "replace" apple IDs, not all data will be transferred with it.

Your subscriptions, keychain, payment info and iMessage chats will not be transferred.

And everything that can be transferred would have to be transferred manually.

If you just want to change the email address of your Apple ID, just try this guide: Change your Apple ID Email - Apple Support

You'll need a computer as a middleman to keep all the data as you take between two apple IDs.

You can get Notes, Reminders,Photos,Files and more via their respective apps on the Mac or https://www.icloud.com on Windows

When changing to the new ID, there may be some data loss, but you can minimize it. If syncing photos with iCloud, ensure Optimization is turned off in Settings/Your Name/iCloud/Photos and/or in Photos/Preferences/iCloud. Then make sure full resolution photos are on the device/computer. When signing out of iCloud, if asked whether you want to retain data, choose yes. Messages conversations will be lost if they are addressed to the ID. See the article below for other places that the old ID should be removed. See Winston Churchill's response in the below discussion. If possible, also set up Family Sharing  between the IDs to keep access to your apps/purchases. 

 How to switch Apple IDs on your iPhone or iPad.      

How to transfer all files from one iCloud account to another.       

What to do after you change your Apple ID or password - Apple Support.      

Family Sharing.         

Family Sharing - Set up.