Just fold a paper into different shapes. Once you achieve something interesting, try with another paper and get the same shape. Then it is repeatable. Anybody can learn it from you. Use any paper. But to get impressed about your own achievements and for others to appreciate your creation use colored paper. Preferably papers with one color on one side and either white are another color on the other side. Ok. Let us choose paper later.
Now take a sheet of paper from a notebook. Can you create square sheet of paper from the sheet of paper you have with out scales and scissors? Try to put one side of the paper on the adjacent of the paper. Tare the excess paper. That is all no more tearing. Hereafter only ORI ORI ORI only. ORI in Japanese language means 'to fold' and GAMI is Paper. So that is ORIGAMI. This is the right time to talk about the restriction I mentioned earlier. It is a simple restriction. That is, you should not tare or cut or paste the paper after you made the square paper. You can only fold. Hey, while trying to make a square paper , I made a triangular sheet. Is it repeatable? Can you create triangle from another square sheet of paper? Yes. Just fold a square sheet of paper along the diagonal. But there is one more diagonal !. Yes. You can fold it along that diagonal also. You get the same result.
What is this. Squares, Triangles, diagonal? Is this origami? Only squares (old fashioned people) do this. It is boring. Don't like mathematics, yet very creative. Hold on my friend. Now open the triangle. Fold the side of the square sheet by placing it on the diagonal line. Now repeat the same by placing the adjacent side of the square on the diagonal line. Now fold the along the diagonal again. Hold the folded paper with you let hand and using right hand hold tip with your thumb and index finger outside and pull it down. Press with your left hand thumb and index finger.
Now you have made the beak of a bird. Make another fold so that you make into a bird having beak neck and body. Now a little about the folding instructions and the terminology. Once you learn these, you can follow instruction in origami diagrams and make hundreds of interesting things.
You can also create your own models and publish.
Valley fold : This is fold you made while making square paper out of the rectangular note book paper sheet. This indicated by a dotted line and an arrow.
Mountain fold : This is reverse of valley fold. That is, instead of folding inside if you fold outside.
Petal Fold: The petal fold lifts a point and brings it upwards so that the two edges of the paper lie together. It is best to pre-fold both layers of paper along the valley and mountain folds before making the petal fold.
Rabbit Ear Fold: Pre-fold along the three valley folds first. Then fold the two sides down to the baseline. Fold the top point to one side to make the mountain fold. (Take care that you fold the top point to the right side where the mountain fold is set.)
Squash Fold: Pre-fold both sheets of paper along the valley and mountain fold. Then open the paper. Fold one layer of paper along the valley fold and flatten the model using the mountain fold.
Reverse (Inside) Fold: Pre-fold both sheets of paper in both directions (mountain and valley). Then open the model a little bit and bring the top point down so that the mountain fold edge becomes a valley fold edge.
Reverse (Outside) Fold: A crimp is used as a way of incorporating two reverse folds to change the direction of a flap or point. In most cases it is easiest just to make two reverse folds one after the other (pre-crease both folds before).
Sink Fold: The sink fold is a method of blunting a point that has no open edges. The fold should first be pre-creased. Then carefully open the model and tuck the point inside. Then, flatten the model along existing creases.
Origami is extremely easy to follow with the help of simple diagrams which are given well in all origami help books, websites, etc. One can get an elementary hold of origami by practicing the basic steps mentioned above.