I would highly recommend  you to puzzle out the properties of the studied characteristics. And only then deal with whatever software. Otherwise, you can get good looking but useless results. E.g., take a look at these old but  very useful articles:

1.  Akselrod S, Gordon D, Madwed JB, et al. 1985 Hemodynamic regulation:

investigation by spectral analysis. Am J Physiol 249:H867-875.

2. "Heart rate variability: standards of measurement...", Circulation. 1996 Mar 1;93(5):1043 - 65. 

If you have any specific questions, don't hesitate to ask.

Matlab, Octave, Python. Escape from the cage. Your ability to do this depends on the data files format - is it easy to decode or not.