Use a dictionary. An English-to-German dictionary is the best way to quickly translate specific words from English to German. However, don't try this method if you don't know any German and you have a lot to translate, because it takes a long time. This works well for one or two words or passages.
Go to a website that offers free translation. There are many, but Babylon, Google Translate, and Free Translation are a few of the more reputable. Type your English writing into the "English" box and then choose "Translate" to translate it into another language. If German isn't already designated, choose German from the drop down list to translate your writing into German.
Take a class in German in order to learn the translations for yourself. If you have to translate very quickly, this won't help you, but it will help you with long term understanding. You can find classes at a high school or college, but you must be enrolled at the school to take them. Some colleges and distance-learning centers offer classes that anyone can take. You can also look at your local extension office for a list of classes your community offers. Or, think about going on an exchange program where you can immerse yourself in a German-speaking country and learn to translate on your own.