I wanna improve my English?

How can i improve my English language skills? This is my foreign language, i mean my second language .I've started to study about 1 year ago, and i like to learn by myself. I'm having problems to get better my grammar/ortographyc but i don't have difficults to understand texts.I also use a site called livemocha; there i usually chat with English speakers and i understand the most of they say. i would like to get fluency in this language but im having problems to fix the writting and listenning! What i need to do ? thnx