Hello,
If you are a beginner with no version yet installed, you should install the latest version which is 7.1. You should also carefully read the instructions and prerequisite for installation, e.g. the need of a compiler, Python or Perl, etc. Telemac is not a simple executable file for Windows, it is able to work on Linux also, so you have to configure a bit and compile before using it.
I must add also that starting directly with oilspills is a difficult thing to do, you should get used before with simple examples involving only hydrodynamics, to understand the basics ins and outs of the software.
With best regards,
Jean-Michel Hervouet