Use Internet dictionaries. Internet dictionaries will allow you to look up the meanings of English words quickly and easily. Look for the pronunciation feature, which allows you to hear how the word is pronounced, so you'll be able to use the words you look up when writing and when speaking.
Read websites that report the news. These are often written in more basic, straightforward language, but they also offer a lot of new vocabulary words. When you come across a word you don't know, look it up in the online dictionary or by typing "define" and then the new word in a search engine.
Listen to podcasts and watch online videos. Hearing how words are used by regular people can help you use them yourself. Also, if you want to hear something a second or even a third time, you have the option to go back and listen to it again.
Read blogs, and pay attention to the comments made by readers. Blogs and comments on blogs are often written in very conversational language. You can get a better feel for how English-speakers talk to one another.