Usability testing is design's moment of truth. You give a real person a realistic task, you shut up, and you watch. No explaining, no hinting, no "oh you just need to". If they cannot find the button, the button is in the wrong place, and the fact that it seems obvious to you is precisely worthless, because you built it.
Write task scenarios in goal language, "you need to email your lecturer, where would you start", never feature language that names the answer. Recruit around five representative users, the research consensus is that a handful of people surface most problems. Ask them to think aloud while they work. Measure success rates, time, and where they hesitate. Then fix things and test again.
Two details separate good tests from garbage. First, who is in the chair. Five of the right users beat fifty of the wrong ones, because wrong participants produce clean-looking data about the wrong world. That car marketplace from earlier tested with polite existing customers and never met its actual market. Second, how you word the tasks. "Find the search page" tests whether people can follow your hint. "You want to know when term starts, go" tests the design. Almost everyone writes leading tasks on their first attempt, which is why the wording gets rewritten more than any other part of a test plan.
Satisfaction lies a little
One more professional scepticism worth having early: people rate things "fine" right after succeeding, because relief reads as approval. Watch what people do, weigh it against what they say, and trust the gap between the two more than either alone.
Ask a family member to find something specific on any big website, term dates on a school site, returns policy on a shop. Say only the goal, then silence. Count taps, note every hesitation and every time they give up on menus and hit search. You have just run a usability test, and you will find at least one problem the site's designers do not know they have.
Steve Krug, Don't Make Me Think, is the most enjoyable book in the field and half of it is about exactly this. His follow-up Rocket Surgery Made Easy is a literal script for running your own tests.