

私の後ろに立ってください。
家の後ろに山があります。
ドアの後ろにだれかいますか。
"うしろに(後ろに)" is in the lesson "Adverbs 1" (Level 23), along with 15 other useful words. LinDuo has 180 topic lessons like this one, 2,379 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.