3 ways I can think of offhand:
1: On the bottom of the main screen click the Classes tab and there is a template button there to apply a template.
2: When creating a new monster (the new creature/monster icon on the toolbar or F5), there is a drop down selector to apply a template below the main text block area.
3: With the desired creature selected (highlighted), use the Windows dropdown menu on the upper left of the DMGenie screen. Select Template Editor (or shift F7) and you will be able to Preview/Apply the desired template.
As noted the DMGenie forums are probably more efficient for such user answers, and the Yahoo groups for additional user-created materials.
hth