kmeans and incom,plete distance matrix concern

Thanks everyone for their help so far. I'm very appreciative of the fact that
people have pointed out that I was heading in the wrong direction.
I would be most grateful if someone could look over the following simple
example for me and tell me if this is how to do it.
I'm assuming by data matrix you mean the 'raw data' organised as a matrix
Data (not euclidean distance) matrix

DF

 V1 V2 V3 V4
1 78 45 34 45
2 97 23 67 12
3  9 56 12 67
4 19 67 23 90
5 34 12 78 56

and then

 clusters.kmeans <-kmeans(DF, 2)

if I want 2 clusters for example.

Am I also right in thinking that I can say which 'centriods' I want the clustering to be done?