There are eight planets in our solar system. In order, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The previous sentence lists them in order from the closest to the sun (Mercury) to the furthest (Neptune)
In addition to those eight planets, our solar system also has dwarf planets. The five most well known dwarf planets are Pluto, Eris, Ceres, Haumea, and Makemake. Ceres can be found in the asteroid belt that separates Jupiter and Mars. The other four dwarf planets can be found in the Kuiper Belt.
The second part of the question is somewhat unclear because it doesn't confirm what "small to big" refers to. I believe that it is asking for a size difference based on diameter and/or equatorial circumference; however, the question could be asking for the planets to be organized from small to big based on mass or density. By estimated radii, the order of the planets from small to large is Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn, and Jupiter. By mass, the order is almost identical Mercury, Mars, Venus, Earth, Uranus, Neptune, Saturn, and Jupiter. Only Uranus and Neptune change order.