download this and have a look at it, it will show you what you should do
The important things are to make an enemy first, which you do by making a new object. Then for that enemy go to their attributes tab and give them at least two attributes such as "life" and "damage". Also then click on the player object and give them the same attributes. Then on the enemy, go on their verbs tab and add a verb such as "attack". Then you will see the rest of what should be added in the game file I uploaded to help.