quick-but important- q!!

im new to my school and the grading system is strange… we do the ib diploma program so in our report cards we get grades on a scale from 1-7 just like in ib…if i wanted to get into top colleges does anyone know what grades i should be getting in my report cards now? i know i should be getting straight a’s but is all 7’s the same or are 6’s also acceptable or what? im so confuzzled :s