You can create a new observation from three different places in iWalkObservation. From the dashboard simply click on any one of the walkthrough tools. 

From the Observations page, you can use the "New Observation" drop down menu to select and start a new observation.

From the individual Educators page, you can use the "New Observation" drop down menu to select and start a new observation.

Once you have selected an observation tool, your first step is to add an educator (if iWalkObservation has not already populated it for you).