Mark the mounting location of the buttons, punch holes in fabric or leather.

Rummage in the tool box, there will always find something to install the button.

The basic sizes of the buttons:

Collect the front part of the ring button.
Expandable tubular part of the button (the button is assembled).   

Should look like this part of the button:
Then resultshowever a tube of suitable diameter rod.

It is important that the rod diameter was less than a Cup of a button.

The install button, it is desirable to produce a smooth wooden surface.

Similarly, set the lower part of the button.

Collect button:

First expandable tubular part (assembled), then resultshowever tube buttons on a flat surface.

Diagram of the installed button:

The front part of the button may be of any diameter.

But when installing the buttons you need to consider the diameter of the round rod of the front buttons.