You don't use "urls" with ancestry member trees. (The urls are different - trees are within the ancestry.com family of data.)
If you have uploaded a tree with FTM2012, you access it in the Plan Workspace in the right-hand panel.
You upload trees to ancestry at any spot in FTM by clicking on the "Share" "Green-leaf" button in the upper-right corner and click on "upload tree to ancestry".
The two web presentations have nothing in common.
Ancestry trees are hyper-linked trees. The old FTM Pages were uploads of FTM reports.