You'd better post this question in the LabVIWE section of the Developer Exchange.
Anyway, I suggest you to look in the examples shipped with LabVIEW: you can find some basic VI that can help to solve your problem.
In Search Examples >> Fundamentals >> File I/O you can learn how to read data from a file.
In Fundamentals >> Graph and Charts you can find examples on how to graph data.
The basic problem is the format of data stored on file: all is easy if they are in plain text, some moreproblem will arise in case they are stored in binary format.
Hope this helps
Roberto