In dishpointer.com website, after selecting your coordinates in a map and also the satellite you want to receive, the satellite's true azimuth, magnetic azimuth is given. Azimuth and elevation has units in degrees.
Azimuth data is useful in rotation of dish in vertical axis and elevation data is useful for rotation of dish in horizontal axis.(here rotation of dish is for ultimate target the satellite in sky)
Out of the two azimuth data, we need magnetic azimuth value for aligning of dish using a magnetic compass. The magnetic azimuth value is already compensated for the local magnetic declination, we can use the value directly.
What is magnetic declination? See below
Hold your phone with magnetic compass app running, in your palm and keep your palm near to your belly or chest, your phone display should be parallel to the earth . Now the compass red needle always points in one direction, that direction is magnetic north. Now you rotate your body on your vertical axis then you will see the degree reading in your phone will vary, that number shows you how much your rotated from magnetic north, now you rotate until you get a reading of 205 degree(for example, this value is given for the selected satellite as azimuth(magnetic)) now the final direction you are facing after rotation of your body is the azimuth of satellite you are looking for, elevation can be adjusted by using the markings on the back of your dish antenna.
For using real compass also the procedure is same but you should rotate the compass only until the the red needle point coincides with zero degrees on the scale below. Now subtract 205 deg from 360 deg you will get 155 deg. Now hold the compass on your palm and rotate your whole body until the red needle points to 155 deg on the scale below. Now the direction you are facing is where the satellite is located in the sky.
Precautions to be taken:
1. The compass should not be operated near any magnetic materials like some metals, and remove the rings on your palm.
2. Do not use compass near the CRT display or any picture tube as it has strong magnetic field surrounding it because of deflection yoke.
3. Do not place compass on the terrace walls or pillar extention blocks as it contains iron rods inside the concrete.
All the above gives you errors in reading.
Use it only by holding it in our palm and take care that no magnetic material is there in the proximity.