Design Advice

Question

I am required to write a C# application that will analyse data logs from a RF control board (multiple RF nodes attached).
The data logs are saved as comma deliminated file(s) - one per day.
The log files are 13 columns wide and 6000 rows down.

I need to analyse the data and display it in a user friendly way - graphical (ie. battery voltages, RF strength, temperature, etc).

At the moment I thought analysing one log file at a time is sufficient but down the track multiple file analysis would be required.

As it's been quite some time since I last wrote a C# application I'm having difficulties determining the best approach.
Thus any design advice/suggestions would be greatly appreciated.
Thank you.