帮我看看下面的一段英文有什么语法毛病啊?

帮我看看下面的一段英文有什么语法毛病啊?
Last summer,I had a chance to go to Beijing as a volunteer for 2008 Olympic game.That activity gave me a valuable lesson for my life.My job was helping those people from all over the world how to get the place where they want to go.At first,I felt a little nervous.But after three days latter,I could feel more comfortable.Although the task was very hard,actually,there were still a lot of fun during those days.This activity provides me an opportunity to practice my English,and improve my communication skills with different people.Olympic game is a great event for everyone in the world.Last summer,when I standing on the land of Beijing,it is my great honor to see this marvelous event during my life,I will never forget that memorable experience.