To write a data frame to a text file, the command is write.table. I'll let you read the help (?write.table) to see all the options, but a sample usage is
write.table(x = mtcars, file = "C:/exported_mtcars.txt")
This will write the data frame called mtcars to a file called exported_mtcars.txt on my C drive. The default is to use spaces to separate columns. If you want tab-separations, specify sep = "\t".
You may want to simply set your working directory to the folder you've created (setwd("C:/Users/...your filepath.../Desktop/your_folder")). Then you can just specify, e.g., file = "file1.txt" for the file names in write.table.
As far as writing multiple data frames to multiple files, I strongly recommend working with lists of data frames. I'll refer you to my answer here on the subject. See especially the section I didn't put my data in a list :( I will next time, but what can I do now?. You can then pretty easily use a for loop to save all your data frames to files using write.table.