about create a R package

Hello, everyone,

I would like to create a package which includes C code. My input data comes from
a text file and I will output my solution into a text file too. My question is
that I put the input file in src directory or data directory or somewhere else?

On the other hand, I want to call this C function from R. Is he R code put in
the R directory or I carry out this code in R environment directly?

maggie