Icon doesn't load
<p>Hi my icons don't load and i don't know why. They should appear in the navigation. Im very new and don't find good new resources to learn. 
Everything is old. Some links would help thank u.</p>

<p><a href="https://i.stack.imgur.com/QIAe7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QIAe7.png" alt="enter image description here"></a></p>

<p><a href="https://i.stack.imgur.com/d79yf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/d79yf.png" alt="enter image description here"></a></p>

<p><a href="https://i.stack.imgur.com/SNneD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SNneD.png" alt="enter image description here"></a></p>