The page shows you the total energy equation to calculate the total energy exist in a system. As pet the total energy formula to find the total energy, square the velocity and multiply it with the mass of the system. Add the obtained value with the internal energy. Now divide the resultant value by 2. On other end, multiply the mass, gravity (9.8 m/s) and height relative reference frame of the system. Add the step 1 and step resultant values, that is the total energy.
Total energy is the sum of all or combination of different forms of energy that exist around the system. You can compute the total energy based on the known attributes mentioned in the total energy equation.