How to transfer concatenated texts from combobox, textfield, and listbox to a listbox?

Okay, I have a combobox that contains the list of ranks (eg. Gen, Col, etc.) and a textfield that the user is supposed to enter the person's full name, and a listbox that contains a list of specializations which are GSC, INF, CAV, MNSA, and FA (multiple specializations can be selected). Now I want it so that when I click a button (add button), their values will be concatenated and placed in another listbox. For example, I selected Gen. in the rank combobox and I typed Albert Einstein in the textfield then selected INF and GSC in the specialization listbox. I then clicked the add button. Now, the other listbox should then contain a value which is Gen. Albert Einstein GSC INF. How can I do that? I'm not really good at javascript. Please, try to provide a simple sample code. Thanks!