Using the blanket that brought baby Kal-El to Earth, Martha Kent sewn together a special costume for her young adopted son, Clark Kent. He dons the Super-Suit and takes on the role of a superhero and protects the town of Smallville. He is eventually given the name Superboy. When he moves to Metropolis, and makes his first rescue, Lois Lane gives him the name: Superman.
His Super-Suit is made from a fabric from Krypton, and as such, the suit is elastic, allowing it to stretch as he grows, and adjusting to his size. It's virtually invulnerable, just as he is. His red cape flutters beautifully in the wind when he is flying. The "S" on his chest is actually the symbol of the House of El, but it shares the appearance of the letter "S," which is what inspired Lois to name him Superman. His suit has no mask, since he uses his glasses to conceal his identity while he's Clark Kent.
Supergirl's Super-Suit is basically a female version of Superman's Super-Suit. She has actually worn several different versions of the suit. Supergirl's legs are almost fully exposed, because her Super-Suit has short shorts.