Start with YouTube. Cookbooks are great and can be interesting, but if you don’t have all the prerequisite skills it can be intimidating.
Pick a dish you’re interested in making - doesn’t matter what. Mac and cheese. A salad. Pad Thai. Search YouTube and skip through a few videos. You’ll probably come across a few creators whose video style really appeals to you. Watch their other recipe videos!
One series I really enjoy is the Four Levels videos by Epicurious. They do a single dish and show it being made by a beginning cook, an experienced cook, and a professional chef (the fourth level is a food scientist who analyzes what the cooks did). You get a wonderful sense for cheap and sloppy ways to make something, and then some ideas on how you could improve on it as you get more experience.
You’re at a perfect age to start this. You’re old enough to understand what’s going on, but still young enough to be able to adjust your eating habits before you start packing on the pounds. That becomes important when you start edging towards 30!