Easiest file method to start with is PRINT and INPUT.
OPEN “UserName.txt” FOR OUTPUT AS #1
PRINT #1, “Joe Smoe”
PRINT #1, “123 Not Here LN”
PRINT #1, “Nowhere, NS 98765-4321”
CLOSE
And the above has written your data to a file.
To read it back, open the file for INPUT and use LINE INPUT #1, variable$ to read that information back into your program.