Once you have logged in, the bar of links along the top of the webpage includes a search box.
To edit the information at the tree node for yourself, or create a tree node, begin typing your name in the search box. A dropdown menu of potential name matches will appear beneath the box.
If a node has been created for you already, either by you or someone else, your name should appear here, along with your affiliation. If the affiliation reflects a previous institution, that is fine. You do not need to create another node.
If your name appears, select it from the drop-down menu.
If your name does not appear, finish typing your name and hit return. A new screen will appear listing all close matches. If someone has created a node for you with a different spelling (a typo or a different middle initial) it will appear here.
If there are no close matches, no names will be listed. In either case, at the bottom of the list there will be a box labeled "Add person".
Clicking on the "add person" box will bring you to a new page, where you can add as much information as you have for that person.