[R] Adding a row at top of dataframe

[ecvetano at uwaterloo.ca]

I have a large data frame 48:2185 with different numbers.
I would like to add only one row at the very top of my data frame with  
0's or NA's.
I don't know which approach to use. Should i create 2 different data  
frames and merge them? Ive also tried the rbind command with no luck.  
I would appreciate some help to achieve what I'm trying to create.
Thanks!