Main streets in Białołęka are ul. Modlińska (parallel to Vistula) and Trasa Toruńska (perpendicular to Vistula)
See the map for the location of bus termini.
If you are going to Zalew Zegrzyński, northeast of Warsaw, you will most probably want to drive through Białołęka. Drive along ul. Modlińska and then turn right in Jabłonna (it's already outside Warsaw). The road number is 61.