First of all, I might recommend asking such DM Genie usage questions on its website (www.dmgenie.com). The forum there is quite active and useful for answering such questions.
Regarding your question, the easiest way to award XP for a trap is to create an opponent via the "New Creature" option and selecting the appropriate trap type/difficulty level from the race selection. Then, once this new creature is created, start a combat with this creature, and see what XP would be awarded from it. You can then delete this trap "creature" afterwards.