There are a few ways to connect a computer to the printer. Repetier Host is a popular program for Windows, Linux and the Mac that allows control, printing, slicing and editing of the EEPROM settings. Other solutions are Pronterface, Simplify3d (which is a full slicer with control built in), or using a RaspberryPi with the Octoprint program installed.   For a USB serial connection, use a baud rate of 115200.