After considering your feedback, it appears that this question goes beyond the typical scope of a StackOverflow inquiry, which usually focuses on specific programming issues or problems. Investing time in familiarizing yourself with JavaScript (a client-side scripting language) and jQuery (a JavaScript framework designed to simplify interactions with web elements across different browsers) will prove to be beneficial. While becoming an expert is not necessary, dedicating a few hours to understanding the basics is highly recommended.
Essentially, you will need to obtain a copy of the jQuery library by either using NuGet or visiting the jQuery website. Once added to your page or MasterPage, you can proceed to create an inline script or incorporate a script file (after adding jQuery) to implement desired effects. I strongly advise checking out the free Try jQuery course from CodeSchool and exploring resources at the jQuery Learning Centre. These sources together should provide ample guidance for achieving your goals.
In addition, I recommend completing the Javascript Road Trip Part 1 course (also free) available at Codecademy to grasp fundamental concepts of JavaScript. You may opt to engage in these courses during downtime once you have addressed initial challenges.
While solving your problem, refer to detailed documentation on jQuery methods and functions in their core API documentation section, as well as JavaScript guides on the Mozilla Developer Network (relevant for all browsers, not just Firefox). Pay close attention to topics like selecting elements, fadeIn, and fadeOut methods. Prioritize reviewing introductory sections on the jQuery learning centre first to prevent unnecessary difficulties later on.