how to focus regular light to make it a laser beam
A laser beam is not just focused light. A laser beam is coherent light. Furthermore, you can't create a laser beam by cleverly focusing regular light, no matter how hard you try. You create a laser beam using stimulated emission. Stimulated emission is what causes the light in a laser beam to be coherent, and coherence is what makes a laser beam so much more useful than regular light. In fact, the word "laser" is actually an acronym that stands for "Light Amplification by Stimulated Emission