Step by step
Drain the potatoes of their oil, add some salt, and then add the beaten eggs to the potatoes in the frying pan, so that the eggs fill in all the gaps between the potatoes.
Tips
In order to make your "tortilla" really creamy, you could add to the beaten eggs a shot glass of milk with half a teaspoon of baking powder dissolved in it.
Trivia
The true Spanish omelette - as loved by Spaniards - is quite thick!