To start using the Evolview you just have to click the "Try me" button on the window.
At the "login" page, click "Use without an account"
At the "mytrees" page, click the folder icon on the "Basic" tab (the only icon that's clickable if no tree is active). in the popup window, enter the following contents and click the button "Submit" at the bottom:
Project: new project
Name: test tree
Data: (chicken,((mouse,rat),(chimp,human)));