There is a link on the Ancestry splash page about signing in. They provide some suggestions for forgotten user name and/or password. If those don’t solve the problem if you scroll down there is a link to contact Ancestry.
The address is https://support.ancestry.com/s/article/Signing-in-to-and-out-of-Your-Ancestry-Account?language=en_US
You don't upload DNA data to Wikitree. You simply indicate the test(s) you have taken. This page will guide you.
Jennie,
In order to take advantage of your DNA test please add it to Gedmatch. It is free. Gedmatch
Here is an old G2G that gives some information.
How does it help you to register at GEDmatch and add your GEDmatch ID to WikiTree?