How do I run .sh or .bat files from Terminal?

This is because the script is not in your $PATH. Use

./scriptname

You can also copy this to one of the folders in your $PATH or alter the $PATH variable so you can always use just the script name. Take care, however, there is a reason why your current folder is not in $PATH. It might be a security risk.

If you still have problems executing the script, you might want to check its permissions - you must have execute permissions to execute it, obviously. Use

chmod u+x scriptname

A .sh file is a Unix shell script. A .bat file is a Windows batch file.

The .sh is for *nix systems and .bat should be for Windows. Since your example shows a bash error and you mention Terminal, I'm assuming it's OS X you're using.

In this case you should go to the folder and type:

./startup.sh

./ just means that you should call the script located in the current directory. (Alternatively, just type the full path of the startup.sh). If it doesn't work then, check if startup.sh has execute permissions.