Start by opening a plan page from the Overview tab, then select "New Takeoff"
Insert the name of what you are trying to measure in the Takeoff Name field ( for example, 3 1/2" PVC).
Choose the corresponding measurement type from the drop-down menu
Click "Start Measuring"
Move you mouse over to the plan page. Notice your mouse has become a set of crosshairs, this indicates that you are now measuring mode. Click on the plan page to start measuring, click once when changing direction, then double click to finish. This will shade the area to show it has been measured.
You can then continue to draw on the plan page, or click the green Finish Measuring button.
You can see your measurements on the takeoff template or in the Reports section
TIP: Create a new takeoff for everything you are going to measure in the project
TIP #2: Some measurement types will ask for additional information after clicking Start Takeoff, such as height, width, or depth.