The quick and dirty way is to download a GEDCOM from Ancestry and upload it here. This will result in a LOT of work for you checking for duplicates, removing all the GEDCOM extraneous data, verifying that the profiles in the GEDCOM have good dates, etc.
The slower way is to download the GEDCOM from Ancestry, then split it into small pieces offline using an app designed to do this and then uploading a small piece to WikiTree. You still have to so the clean-up but it is a lot more manageable.
The best, most accurate way is to build your tree here one person at a time, checking to see if that person is already here, and adding sources to all your facts.
I've been there and done that with a small GEDCOM and it's a lot of extra work.