How to ride faster?
Without getting too technical about training methods or overthinking it, just ride with people a bit faster than you, but not so much faster that you get dropped in 20 or 30 minutes.
Find a local group ride that's at a level that you'll get dropped from in about an hour or 90 minutes. Then keep doing that ride until you don't get dropped. Move up to the next faster group. Repeat.
Do rides like that once or twice a week - no more. Because they're hard on you, and if you do them day-after-day you never recover, never really get stronger. You'll only get good at being mediocre if you go hard day-after-day-after-day.
During those rides, don't think - just ride. Learn how to pay attention to your body so you know how to control your efforts so you don't blow yourself up.
Get a cheap bike computer that has a cadence meter - work on keeping pedaling all the time, and pedaling at 80-90 RPM constantly. It'll probably seem hard at first, but in the long run that will really help your endurance.
2-5 times a week go for easier rides, where you ride for an hour or 90 minutes at a decent but not really hard pace, but trying to never stop pedaling - the purpose here is to build up both your muscular endurance and aerobic power levels, and taking breaks to recover defeats that. Maybe once a week throw in some three to five 5-10 minute-long hill repeats where you go up a hill at a relatively slow but steady pedaling RPM, say 50-70 RPM, to help your climbing. Or maybe three or four 5-10 minute intervals where you pedal at a high RPM (100-120 RPM - this is harder than you'd think if you've never done it...) with no breaks - that builds and widens your effective "torque band", helping you to respond to changes in pack speed without killing yourself, and also improving your top-end sprint speed.
Bottom line: don't overthink it. It's just riding a bike.
If, after you get some more experience, you want to do things like buy a HR monitor or power meter and get into a more structured training program, then you can start worrying about details.
But until you can do something like a 2- or 3-hour ride at a good speed without stopping and without feeling like your legs are turning into cramp-filled pretzels, you don't really need to overthink things.
As someone once said, "Ride lots".