I have existing Ipad with music on it which is an old Apple A/C , my son has access to that one, I now have a new Iphone 6S on a new account as I couldnt remember old log in details, since I only used it to load music to Ipad yrs ago

Hi Mark,

Congratulations on the purchase of your new iPhone 6s! The music that is on your old iPad would have been synced from your Windows PC. Do you still have access to the iTunes Library on your computer? If so, you would connect your new iPhone to your Windows PC and sync the music or playlists that you wish. If you purchased music from the iTunes Store, you would need your old Apple ID and password to add the purchased music to your iTunes Library or to your iPhone. I'll include some information below to get you started.

iPhone User Guide for iOS 9
http://help.apple.com/iphone/9/

Frequently asked questions about Apple ID
https://support.apple.com/en-us/HT204161

Your Apple ID is the personal account you use to access Apple services like the App Store, iTunes Store, iCloud, iMessage, the Apple Online Store, FaceTime, and more. Use the same Apple ID everywhere you sign in to make sure that all your Apple services and devices work together seamlessly and you can access your personal content from all your devices.

How do I sign in?

Any time you set up a new device or access an Apple service, you'll be asked to sign in with your Apple ID and password. After you sign in, you'll gain access to the service and all the personal information in your account. Services that use Apple ID include iCloud, iTunes, iBooks, the App Store, FaceTime, Messages, Game Center, iCloud.com, and more.

You can also use the steps below to sign in on your iPhone.

iPhone, iPad, or iPod touch

• Tap Settings > iCloud
• Tap Settings > iTunes & App Store
• Tap Settings > Mail, Contacts, Calendars
• Tap Settings > FaceTime
• Tap Settings > Messages > Send & Receive

What if I can't sign in?

If you can't sign in, check your Apple ID to make sure that you're signing in with the correct Apple ID. Then try the steps below:

• Reset your Apple ID password if you forgot it.
• Get help signing in with two-step verification.
• Regain access to your account if your Apple ID was locked.
• Get help if you’re asked for the password to your previous Apple ID.

If I purchased music, apps, or books with multiple Apple IDs, how do I move my content onto my iOS device?

First, make sure that all your content is on the same computer. This computer should be the one you sync your device with. Use these steps to copy content from your Mac or PC.

Then authorize your computer to play content with each Apple ID in iTunes. After your computer is authorized for all of your content, you can sync it to your iPhone, iPad, or iPod touch.

Move content from iTunes on your computer to your iPhone, iPad, or iPod touch

https://support.apple.com/en-us/HT201593

Learn how to manually add specific songs or videos onto your iOS device from your computer.

By default, iTunes manages the content of your iTunes library (including your music, TV shows, movies, and more) manually, which gives you control over the content you want to take with you on your iPhone, iPad, or iPod touch. This is useful if your iTunes library contains more items than can fit on your device.

Manually add items to your device

1. Connect your device to your computer.
2. Open iTunes. Make sure that you have the latest version.
   
   You might see a message that your device is synced with another library. This means that you've used a different computer to sync your device in the past, and iTunes can't sync without first erasing and replacing all iTunes content on your device.

   If you're using an iPhone, you can only add music or video from a single iTunes Library.

   If you're using an iPad or iPod, you can add music from multiple iTunes Libraries, but video from only one iTunes Library.

3. Choose the content that you want to add to your device from your iTunes library.
   
   

Drag the content to your iPhone, iPad, or iPod. A panel should appear. Locate your device.

Cheers!