If a term base is attached to your project, the TB field on the bottom right side of your Editor screen is green. In such projects, you can enter new terms on the run while translating in MemSource Editor. To do so, press CTRL+T to open a window for entering new terms. You can either type the source and target terms manually, or highlight them in the text and press CTRL+T which will copy & paste the terms to the corresponding fields. Then make the necessary settings (case sensitive, etc.) and hit Enter. This will add the term to the MemSource term base attached to the project in the write mode.
CAT Tool entries interpretation
When you click onto a TM or TB entry in the right hand pane, the date, author and other additional details for this entry are displayed in the window on the bottom of the pane.