I need to transfer from a laptop based program to on-line. How do I upload my last return for 2023 reference ?

See the following FAQ.

How do I transfer last year's return into TurboTax Online?

In the FAQ, click on "If you used the TurboTax Desktop software last year" for detailed instructions.

First of all the Online version won't open for a couple weeks so keep checking back.

Then You will need to have the .tax2022 file on your computer.  If you used the Desktop program last year here’s How to transfer into the Online version, expand the blue link if you used the CD/download last year........

https://ttlc.intuit.com/community/entering-importing/help/how-do-i-transfer-last-year-s-return-into-turbotax-online/00/25953

If you used the Desktop program before you may not like the online version.  It has less features and no Forms Mode.  You can only do 1 return.  Your return is only saved online so be sure to save both the .tax2023 data file and the pdf file to your computer when you are done.  In case you need to amend in the future or if you need a copy to get a loan or something.  You might not be able to access your online return when you need a copy.