Given a DataFrame:
s1 = pd.Series([1,2,3])
s2 = pd.Series(['a','b','c'])
df = pd.DataFrame([list(s1), list(s2)],  columns =  ["C1", "C2", "C3"])
print df
Output:
  C1 C2 C3
0  1  2  3
1  a  b  c
Lets add a new row, [10,11,12]:
df = pd.DataFrame(np.array(...