If you need to know how to do the basics look here and watch the videos a punch and a proper punch are two different things.
Stances: There are three types of stances in Tang Soo Do Front Straddle and cat.
Front Stance
The key to the front stance is to put equal amount of wait on each leg. Both of your feet must face forward. This sets you up to do a proper kick. One more thing is that you need to have your chest always facing forward. This is hard to tell you about over the internet. Please look at picture for help.

Straddle stance
This is more complicated then the front stance. Everything must face the same way. Then just get down low.

cat stance
This stance has nothing to do with the cat if you're wondering. The trick is to put all you wait on you back leg. This will be hard at first but to know if you're doing it right left you front leg off the ground. If you don't have to move your body to much you're doing it. For this I made you a video.
Punching
To punch always use your back hand. When you punch you need to start with your palm up then in the middle of you punch twist your hand. This will give you more power. Also stand on the toes of your back foot and lean forward this also gives you much more power.
Front kick
This is the only kick I will give to the public. The first thing is to get into a front stance. You need to use your back leg for this. First you lift your knee. Make sure you leg and foot are still pointed toward the ground. Then swing your leg out in front of you with all your power. When your foot hits makes sure it strikes with your heal.
The last advise
The last piece of advise I have for you is to keep your hands up. That is so if you get punched at you can block it. For more info all you have to do is join master Alegria in San Pedro. He is off of 22nd and western. I have trained under him for years. I am now a black belt and hoping to open a dojo of my own when I grow up.