If you wish to store data for upload into R from Internet, Gist (from GitHub) is a convenient option. You need to register (if you haven't done so far) and create your account on GitHub, and then create Gist file. Free plan offers storing unlimited number of files, which are public (you cannot hide them); if you need to store data you don't want others to see, you need to pay. In most cases, however, public sharing is ok (it is unlikely that someone can use your data unless you provide a guidelines what data are in).

Follow the screenshot images below to see how the data were uploaded into Gist and then loaded into R from Gist. The script used in R in the end of this tutorial (with link to data) is here:

imported_data <- read.delim ('https://gist.githubusercontent.com/bob-tester/f405f5738ffd6a62ae4f64f150825d59/raw/e43ee6e03e1432c3819630c023fda515b8fc08e5/data-for-import.txt', row.names = 1)
plot (imported_data, type = 'l', col = 'red')