Everyone should know how to see on a button and cook at least two meals from scratch. Here is how to sew on two and four hole and shank style buttons.
For your ease in seeing what to do, I used contrasting thread, buttons and fabric. Preferred method is for the thread to match either fabric, buttons or both.
Step 1: Thread a Needle
Using a clean cut with no hanging filaments, slip the end of the thread through the needle. Pull through about 5 inches of thread, then cut the thread from the spool about 5 inches from the eye of the needle. Holding the two ends of thread even, wrap the double strand once around your forefinger, and roll the thread between your finger and thumb. Pull it tight with your other hand, catching the thread with your thumbnail to make the knot.
Step 2: Mark Placement
If you are replacing a missing button, there will often be a hole or threads marking the placement, if not, or if you are moving the placement, use chalk or a washable fabric marker or a pencil to mark where the button goes. The easiest way is to lay the garment out with the buttonhole side overlapping as it will when you are wearing the garment, and marking through the center of the buttonhole.
Step 3: Attach Button
Pass needle with thread from inside of garment to outside through your mark. Slip needle through one hole of button (or through shank) and pull thread through until button is against fabric. Pass needle through next hole, or other side of shank. If using a two hole button, make sure holes are lining up the way you want them. Repeat process at least four times through the two holes or around the shank. For four hole buttons do one set of holes, then starting with needle inside garment, switch to the other set of holes and repeat at least four times.
For a vintage look, cross to second set of holes on the outside of garment, rather than the inside for four hole buttons. You can also do them as a cross instead of two bands.
Step 4: Finish the Job
On back (inside) of garment, secure thread by taking three small stitches in the same place. Cut thread close to fabric.
For a heavy use shank button, use needle to tie a couple or three knots around the thread holding the shank before securing the thread on the back.