Complex sentence: The original stadium had only the bleachers behind the first base dugout, now the bleachers have been extened from behind home plate to the left field foul pole and adding extra sections down the right field line and in left center field.
Split into simpler sentences: The original stadium had only the bleachers behind the first base dugout, but now the bleachers have been extended from behind home plate to the left field foul pole. Aditionally, extra sections have been added down the right field line and in left center field.