www.wordreference.com
This online dictionary gives you definitions in English. Click on the dictionary, type in the word that you do not understand and then get a definition in English.

http://dict.leo.org
The next dictionary gives you an English-German translation. Type in the word that you do not understand and then get German translations.

www.babylon.com
This dictionary gives you an English-German translation. You have to download it first. But then it will always be on your computer and ready to help you when you are online.