Single-Page Design Portfolio Using HTML, CSS, and JavaScript

Any of my JavaScript legends out there can you please help me!?!?! I am still at a novice level when it comes to JavaScript so it took me forever to figure out how to get the image slider to transition the images but its only transition the first image and does not slide the images left or right when you click the arrows. If anyone is good with JavaScript transitions and animations and could help me out I would deeply appreciate it! Also, I cannot keep the images from overflowing the slider-container even after using "overflow: hidden" on the parent container so if anyone knows what's up with that you would be greatness!