i have forgotmy apple id and password.. also locked my device.. im the 1st owner.. how mshould i find my apple id

See If you forgot the answers to your Apple ID security questions https://support.apple.com/en-us/HT201485

Given what you say, I think it is extremely unlikely that you will be able to answer your security questions. If you know you won’t be able, or haven’t been able, to answer these questions satisfactorily, see

Security and your Apple ID https://support.apple.com/en-us/HT201303 says “without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account.”

So, assuming you won't be able to deal satisfactorily with your security questions, you won't be able to help you with your problem unless you have an extenuating circumstance (e.g., you have the receipt for the purchase of the pertinent device with its serial number on it). If you have an extenuating circumstance, even one not mentioned above, then use the support options below:

Get a call from Apple support to help solve her problem using this

link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific and

region-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help https://getsupport.apple.com/. Go through

the options to find the best support option.

See if you can recover the ID/password.

Apple ID - How to find your Apple    An iCloud e-mail address is an Apple ID.

Apple ID - Find              

Enter the Apple (iCloud) ID and click Forgot Password.

Apple ID - Manage            

Apple ID – Forgot Password            

If necessary, if you are the original owner, contact Apple ID Support. Apple Support will need to see the original purchase receipt with the serial number/paperwork.

Apple ID - Official Apple Support.    

Contact Apple for help with Apple ID account security - Apple Support.  (Link doesn’t always load)   

Get Support      Work through the screens to get a chat option. 

https://twitter.com/AppleSupport