I run R on Windows, and have a csv file on the Desktop. I load it as follows,
x<-read.csv(\"C:\\Users\\surfcat\\Desktop\\2006_dissimilarity.csv\",header=T
A simple way is to use python. in python terminal type
r"C:\Users\surfcat\Desktop\2006_dissimilarity.csv" and you'll get back 'C:\Users\surfcat\Desktop\2006_dissimilarity.csv'