My experience has been that almost always the name of the program I've installed is all I need to run it. For example, I installed the xplns astronomy program, and to run it all I need to do is type "xplns" (without the quotation marks) in a terminal window. If you want to run the program in the "background," so that you can close the terminal window after you're through (or use it for something else), type it this way (without quotes): "xplns &" and the ampersand tells the system to run the program in the background.
If typing what you think is the name of the program doesn't work, try
"man [name you think it might be]" or "which [name you think it might be]" with different combinations that sound likely. "Man" will give you a rundown of the options you have when you run the program; "which" will show you the location of the program, in case you need to specify the directory it's in (unlikely). "whereis" (one word) is a command similar to "which" that you can also use.
Hope this helps.