This exercise is going to show you how to get values from the graph. From the graph below, to get the y value of say x = 3.14, first, type in x = 3.14 into the input column. A line will be drawn intersecting the graph. Next select the intersecting icon from the drop down under the points icon . Next, click on the 2 lines, the graph line and the x=3.14 line. A point should be made on the intersection point. You can now read the y value from the point in the input column. (3.14,y value). You can clear the intersecting line x=3.14 either by selecting it and deleting it or just hide it by clicking grey colour dot beside the equation of the line in the input column. Try finding the value of x when y=1.2.
Another faster way would be to use the point icon and click at any point of the graph. To ensure the point is exactly on the graph, see that the graph is highlighted first before clicking. Using the select tool, move the point along the graph until you get the desired values. This method is however less accurate.