Protein Folding and Its Main Influences

What are the main influences on protein folding? How do hydrogen bonds form during protein folding into secondary structures?

Proteins organize themselves into specific three-dimensional structures through a myriad of conformational changes. What are the main influences on protein folding? How do hydrogen bonds form during protein folding into secondary structures? How do the different classes of amino acids (nonpolar, polar, charged) influence tertiary protein structure?