I have a txt file that I have successfully opened and I need to Map RefSeq IDs to gene IDs and then make it into a table. How would I do that using R? I have no idea where to start. When I open the txt file it is two columns of the Refseq as well as the peptide but I don't know how to match them with a gene sequence using R in Bioconductor. I have downloaded all the packages already. Please help.