More than "everything", pick one program and stick to it. For beginners,
the 5x5 is a good place to start. All basic compound movements that work the whole body, and very efficient if you don't have a lot of time to spend in the gym. Once you've pinned down good form and have a basic level of strength, you'll want to increase the number of reps to 8-12, known as the "hypertrophic range" because that breaks the muscle down, and when you rebuild it during recovery you'll gain size. Personally I stick to low rep counts because I don't want to get big and just want to lean out.
If you want to gain mass, you will need to eat more calories than you're burning. Tracking macros is good and can help you to optimise for maximum gains, but if you're starting from a place of junk food it's like someone who hasn't learned to walk yet trying to snowboard... There's a lot to learn about diet and nutrition, and even junk food/high GI foods like white bread/rice can be used (at the right time) to maximise gains. But all of this is too complicated for a beginner and would not be sustainable if you tried everything immediately. I'd suggest just trying to start small, do it consistently, and move towards a healthier diet with more high quality protein in it (lean chicken, turkey, fish). Creatine is again another "optimiser", and I don't really bother with it on my current program (some people I know also take branched chain amino acids and beta-alanine), but I do take whey, a whey/casein blend or soy protein as supplements depending on which part of the program I'm on and time of the day.
The main thing is to start with the basics, lift heavy, ensure that you're getting enough protein and to clean up the diet. DO NOT STARVE YOURSELF. The first thing that the body burns after all of the glycogen is gone (which happens quickly, within a day or two) will be muscle. Another thing: doing a lot of cardio burns muscle, which is why the bodybuilders avoid it like the plague (unless they're doing a cut, then they adjust their diet to protect against this). But cardio is essential to cardiovascular health, so I'd suggest doing about 20mins of moderate stuff like stair-climbing, walking on the treadmill at an incline or jogging 3-4 times a week.
As for how much protein is "enough", bodybuilders tend to overkill with up to 2g/lb bodyweight per day. Even elite athletes only take about 1g/lb, and research shows that beyond 0.8g/lb there's no subsequent gains. I eat in the range of 0.8-1g/lb, only because protein also has anabolic (muscle building) effects and while it's easy for the body to convert sugar/carbs into fat and obviously the body stores fat as fat, it's not as easy to do the conversion for protein. That's helpful if (like me) you're trying to lower body fat % or maintain it at a low level. Cost is a consideration of course, since carbs and fats are cheap, but since I'm an Asian female and weigh a paltry <130 lb, I can fulfil my protein needs without costs going through the roof.
For scale of how much protein you'd expect to get from meals:
- half a chicken breast with no skin/bone gives you about 27g of protein
- turkey breast is 24g/100g
- a can of tuna (in water, you'll want to avoid brine/saltwater because it causes water retention which means that you'll balloon and end up puffy) is ~25g
- 1 scoop of whey protein in water ~24-30g, depending on the brand/type
- greek yogurt (I typically eat Fage so this macro value is from there) is 10g/100g serving
- low-fat cottage cheese is 14g/half cup
- egg: 6g/large egg
- 2% milk 8g/cup
- egg white (you can cook this in an omelet, NEVER drink it raw because it contains avidin which inhibits your absorption of protein) 26g/cup
These are common sources of very lean protein (protein:calorie ratio is high), which is why bodybuilders tend to rely on them as stock foods. There's quite a few more, like oats etc. but remember that if you want to bulk up, you will need to ensure that you eat more calories than you burn, i.e. you can't just eat the above foods because they're very filling and you'll probably end up losing weight. Calorie-counting is flawed, but there are some things that it's useful for as a ballpark estimate, and that's why people who are starting out keep food diaries. I did it for about 3 months while trying to build muscle, and have a good enough gauge now to ballpark almost anything that I eat. I don't bother with counting calories unless I'm working towards a specific goal, and that's generally how people use that system. Right now I still generally keep track - not to try to lose weight - but to ensure that I'm eating enough because I run so much and eating high-protein/fiber means that I feel fuller and might not get enough calories.
It's really about making the physiology/biology of the system work for you.. and once you understand how your body works, it's quite straightforward to manipulate it to get it to where you want. There's several other systems as well, but I think you'll want to start with something very basic and do it consistently before trying them.
...yeah I could write a book on this stuff.
