For this achievement, first select "2010 FIFA World Cup" in the Main Menu.
In the following screen, you can change the settings if necessary.
If you're not as skilled as you'd like to be in FIFA, you can set the difficulty to "Amateur" and change the fixture type to "individual", this way you can select all the teams for the World Cup manually and make sure you can beat all of them.
Either way, make sure to select South Africa as your team, pressing when the cursor is over the team and press to continue.
To get the Achievement, simply finish 1st or 2nd in the group stage and advance to the knockout stage.