How do I swaddle my newborn?

Don't.... ..Swaddle the legs together and straight, it can worsen hip dysplasia. "frog leg, knee up" is the best position for the baby's legs. Swaddling arms to keep the baby from scratching herself is probably ok for the first month or two.
I should draw this. Place a small blanket onto a bed/surface in a diamond position with the top corner folded down. This is where your baby's head will go. Then take on corner at the side and cross it over your baby then tucking it under his bottom. Now take the corner by his feet, cover the feet and bring it up and over the shoulder opposite the side you tucked. Then the remaining corner crosses the body.
Don't bother. Swaddling is simply wrapping baby tightly because some newborns feel more "at home" this way. After months in a tight womb, the freedom to move arms and legs is scary for some. Newborns should be encouraged to adapt to this freedom, loosening the wrap progressively until it is removed as soon as tolerated. Once baby starts to move more, they can suffocate in the blanket.