To start Star CD, copy the file star.csh in your home directory and source it.
Then type prostar in the command window.  You must choose the file to open or type a new name for the session.
It opens the Prostar window with the graphic interface and the STAR GUIde.

To compute a calculation, you can do it following the different steps of the STAR-GUIde (which opens at the same time that the Prostar window).

Here is a list about some points that you had to be very careful with :
 

Star CD only works on 3D geometry or "pseudo 3D".
It means that if you want to work on a 2D problem you have to define a dimension unit in the third dimension.
In the Create and Import Grids item, use Create Grids and then Create 2D Grids item. Begin with the button Generate 2-D Mesh to create the 2D geometry and then use Generate 3-D mesh from 2-D mesh.
 

You first define the boundary regions in the Locate Boundary chapter but you choose the parameters of these boundaries in the Define Boundary Condition chapter.

• If you want to define a User subroutine :

Find the concerned subroutine with Utility and User Subroutines menu in the ProStar window.
Copy the original version of the subroutine with Write File command in a subdirectory called ufile in the current working directory.
Then edit the file and add your coding part, save it.
As you were running the analysis with the GUIde answer YES to the question "Do you have User Subroutines ?".