Ashwin, in order to have your first approach to Eclipse I suggest you to check in first place the data files that come along with Eclipse (search your installation folder, Eclipse, data folder). Read any data file carefully with the Reference Manual at hand, try to understand what every keyword says, then run the model and visualize it using FloViz, re-read the data file and check that what has been written is also shown in the 3D window. There are plenty of examples in that folder, at the end you'll be able to build a simple grid by entering the code directly to the data file.