Say ten times:

اللَّهُمَّ صَلِّ وَسَلِّمْ عَلَى نَبَيِّنَا مُحَمَّدٍ

O Allaah, send prayers and peace upon our Prophet Muhammad.

Allahumma salli wa sallim 'alaa nabiyyinaa Muhammadin

The Prophet saw said: "Who recites blessings upon me 10 times in the morning and 10 times in the evening will obtain my intercession on the Day of Resurrection".

At-Tabrani, Sahih at-Targhib wa at-Tarhib 1/273.