Hello Ms.paradee:
It is very convenient to get to your hotel. You can take Beijing airport express train from T3 and transfer to the line 2 at the Dongzhimen station. After 3 stations you will arrive at Jianguomen, transfer to line 1 and get off at the Tiananmen Dong at the Exit of B. Continue walking along the Changan East street and turn left when you meet Nanheyan Dajie. THen you'll see your hotel. Good luck~