How do I add my iPad to my account please

Have you turned on the iPad and started the iPad activation process?

Set up your iPhone, iPad, or iPod touch - Apple Support

If you can't remember the Apple ID and password you originally setup for this iPad, then you have a major issue.

You will never get past this.

Apple maybe able to help IF you can find the original sales receipt ( either paper or email receipt ) for this iPad ( or even the box which has the iPad serial number on it ),

Search online to locate and call contact your nearest, “local” Apple Store location to make an appointment to get your Apple iPad reset, if you have any or all of this info.

OR, failing that,

Contact Apple support via the contact support link located at the upper right hand corner of every Webpage of these Apple support communities OR by installing and using the Apple Support app found in the iOS App Store.

Tap the iOS App Store link below.

https://apps.apple.com/us/app/apple-support/id1130498044

Best of Luck to You

Did you purchase this iPad new from Apple/Apple reseller or purchased a second hand, used iPad from some other untrusted source?

Sorry to learn.

Apple does not keep personal sales records.

So, it is up to the owner of the iOS device to prove original ownership.

If you have the box, the box has the serial number.

That maybe of help to Apple, but maybe not as this does not really prove proof of ownership, but it maybe worth a try.

Sorry & Best of Luck to You!

It won't matter, either, as I believe the all the data on that iPad maybe already lost when the iPad went into user activation lock.

Unless you can remember the Apple ID and password you used ( it is still a really good idea to write all of this login ID and password info down, for all places on the Internet you regularly visit, rsomewhere, like in a notebook or paper pad, so as our memories start having issues remembering things, later in life, there is a paper record of all this info for the future ), then this data is lost/gone an attempted reset ( if this was a possibility ) would totally erase the device and reset it as new, wiped/clean device.

Sorry.

Sorry I did not have better news for you.

Michel