Skills for your hero are free for entry levels and sometimes overlooked or not understood. This is a step by step walk thru on how to use them and activate so they work for your hero.
First make sure your power is full as power is what will be used to do the skill upgrades. Then go to your skill tree and open it.
Now follow the tree line up, upgrading what is needed and what your level allows.
To upgrade something click on it, then click “upgrade”. Once finished upgrading, click it again and “assemble” it to add it to your heros skills.
You will now see your heros skills at the top, your power points have dropped from what you spent and you will now have the added bonus from what you decided to take.