6- Bowing (Rukoo')

After completing his recitation, the prophet (sallallaahu 'alaihi wa sallam) would pause for a moment, then raise his hands in the way described earlier , say takbeer

Allaahu Akbar
This means: Allah is the greatest

Notes :

1- You should raise your hands with the takbeer. Look at the picture
2- Be careful: When you start to pray don't look at the sky because it is forbidden as the Prophet peace be upon him said :" People must refrain from looking up at the sky in prayer, or their sight will not return to them (and in one narration: or their sight will be plucked away)

Then .. you make Ruku' and say :

Subhana Rabbi yal azim

This means: How Perfect is my Lord, the Supreme!

Note :

Be careful:

The Prophet said : Verily, I have indeed been forbidden from reciting the Qur'aan in rukoo' or sujood. In the rukoo', therefore, glorify the Supremity of the Lord, Mighty and Sublime, in it; as for the sujood, exert yourselves in supplication in it, for it is most likely that you will be answered ...so it is forbidden to read Quran in Rukoo' or Sujood

http://www.islamway.com/english/images/prayer/pray6.htm