Hi.

To answer your first question, the easiest way to find the format of your video file on your computer is to download and install the free MediaInfo and, perhaps, the free GSpot.  Point either of these utilities at your file and study carefully the information you see.  It will include details of the file format.

Your second question is a little less easy to answer directly.  What format are you starting with and what do you want to convert it to?  There are a variety of programs, most are free, which will allow you to convert from one format to another.

Jeff