There exist two possible ways of adding new entities to your - standard type - diagram. The first one is the following:
[If you do not already have a project-based diagram open (see section 2.1 above - option 'Open Diagram')] From the File menu select New Diagram of Type and then Standard Diagram (database driven);
Point the mouse inside the main, white panel and right click. Select the first item of the menu: Add, and then one of the three items that come up: Individual, Chromosome_Example, Clan_Example. Regardless of which one you choose, an entity represented by a small square will appear in the main panel.
Select the just mentioned item; a table at the bottom of the page will open with several fields to fill in. The fields vary for the different entity profiles mentioned in the previous point. Once you have entered the required information click again on the entity, it will change accordingly (e.g. depending on its gender the square will turn into a circle or a triangle).