debugging R

[Fred J.]

Hello
I have some lines of code I wish to debugg. so I type
in the ehco area M-x gdb <Enter> I get 
Run gdb on file: C:/somedir/file.R/sourcecodefile.R
I get
NO such file or directory, gdb

what am I doing wrong?

I am trying to follow this but I need more explanation
on what it means
"
A third option is to start an inferior R process via
ESS (M-x R) and then start GUD (M-x gdb) giving the R
binary (using its full path name) as the program to
debug. Use the program ps to find the process number
of the currently running R process then use the attach
command in gdb to attach it to that process. One
advantage of this method is that you have separate *R*
and *gud-gdb* windows. Within the *R* window you have
all the ESS facilities, such as object-name
completion, that we know and love. 
"
it says I have to give R binary, well the
filesourcecode.R is a text file, what then?
and how do I do this ps + attaching the command thing?
thanks