How to order specific MODIS tiles from Reverb

Using Reverb's 2D coordinate data search. http://reverb.echo.nasa.gov/reverb/
In the spatial search box with the map, click on the drop down menu in the top left corner.
Select 2D coordinate.
Now, in the Coordinate System drop down menu, select MODIS Tile SIN (this refers to the sinusoidal grid that the data is in).
Next, you can either enter the horizontal and vertical coordinates in the top field or use the sliders to specify your tile coordinates.
Horizontal = (x) , Vertical = (y)

To specify your data set you can enter the data set short name (e.g. MOD10A2) in the search terms field at the top right corner of the interface.
Then enter a time period or range if you need one. Select the dataset, search for granules and continue through the selection and ordering process.