Step one is to load your data into R (some tips https://r4ds.had.co.nz/data-import.html).
After that, one tool in R that makes these kinds of filter operations quite easy and intuitive is the dplyr package. For a nice introduction to how this works check out the vignette here;
https://cran.r-project.org/web/packages/dplyr/vignettes/dplyr.html
This guide will help you get up to speed with dplyr's select and filter functions, which based on your title I think you are looking to get familiar with.
Since you're getting started with R, I'd encourage working with the R4DS book, online here https://r4ds.had.co.nz/ It's a nice way to learn about how to take advantage of R for data exploration
As you run into specific issues (say, specific coding issues, with errors messages, or output you weren't expecting), this forum is a good place to seek help and advice. We have a nice guide for R coding questions here: FAQ: Tips for writing R-related questions