Check boxes and combined text output

I need help with code for a combined text box output.

A. Input: The user should choose among different checkbox options.

B. Output: The selected text strings should go collectively to an updated text box. The textbox should update instantly as the checkboxes are selected, so you will se the final result directly.

C. Transfer: By clicking a button the content of the text box should copy to memory for later insertion in other software.

Any suggestions?