WGBS Data Analysis Related

Hello

I am working on WGBS Data. I am using MethylSeekR package. From vignette I can see that I can give my input file using the below mentioned command.

system.file("extdata", "Lister2009_imr90_hg18_chr22.tab",package="MethylSeekR")

As per my understanding is concerned, this extdata will be my input file. My question is

1. in which format (file format) it has to be given?

   and

2. what is the command to make this extdata?

Thanks
Shrinka