The following is a rough timeline of the events in the Red Mars Trilogy.
2020 - The first manned mission to Mars occurs, with John Boone being the first person to set foot on Martian soil. It is organised by NASA. In the following months and years, NASA and Russia send several unmanned spacecraft to Mars in order to supply a future colony.
2024 - The USA and Russia begin construction of the Ares spacecraft, hoping to establish a small colony on Mars. Construction is mainly done in Earth's lower orbit using parts from other spacecraft, like decommissioned space shuttle fuel tanks.
2081 - Green Mars begins.
2225 - Blue Mars ends.