How to find the details of all methods used in Flexigrid

Please help me to understand the concept of Flexigrid.
I have added Flexigrid with all the functionalities.
But i am finding it difficult to understand the actual meaning of all functions used in flexigrid

For Ex:
1)url: '@Url.Action("UploadFiles")',
paramname: 'files',
maxFiles: 5,

2) [HttpPost]
public ActionResult UploadFiles(IEnumerable files)

3) private byte[] ReadData(Stream stream)
{
byte[] buffer = new byte[16 * 1024];

using (MemoryStream ms = new MemoryStream())
{
int read;
while ((read = stream.Read(buffer, 0, buffer.Length)) > 0)
{
ms.Write(buffer, 0, read);
}

return ms.ToArray();
}
}

Any help will be appreciated.