how to use R

sorry i am a novice so my question is I am trying to run R script but i am not able to do so. I use darwin to run the script

#R script to read the GRM binary file
ReadGRMBin=function(prefix, AllN=F, size=4){
sum_i=function(i){
return(sum(1:i))
}
BinFileName=paste(prefix,".grm.bin",sep="")
NFileName=paste(prefix,".grm.N.bin",sep="")
IDFileName=paste(prefix,".grm.id",sep="")
id = read.table(IDFileName)
n=dim(id)[1]
BinFile=file(meta, "rb");
grm=readBin(BinFile, n=n*(n+1)/2, what=numeric(0), size=size)
NFile=file(meta, "rb");
if(AllN==T){
N=readBin(NFile, n=n*(n+1)/2, what=numeric(0), size=size)
}
else N=readBin(NFile, n=1, what=numeric(0), size=size)
i=sapply(1:n, sum_i)
return(list(diag=grm, off=grm[-i], id=id, N=N))
}

why can't it find the file?