Study. Lots of what you've read here is garbage.
I wouldn't say everything else is here is garbage (I think the other posters are trying to summarize the OP's BROAD
question as much as possible)...but obviously chuckystud knows his shit
and I completely agree with him when he says: STUDY, STUDY, STUDY, instead of going around asking other guys.
Seriously, Tom, there's sooooo much to learn, and you're starting all the way from the beginning. I remember what that was like. But you're not gonna get sufficient knowledge from just one question.
The fundamental advice I have for you is:
1) I'm gonna reiterate chucky's advice to STUDY. READ articles. Start with maybe a light-fitness publication like Men's Health or Men's Fitness. Take a lifting program from there, and learn the basics.
As you progress, get more serious, you learn more, and are able to understand more advanced advice from, say Muscle & Fitness, MuscleMag, bodybuilding.com, and eventually T-Nation. Study, read articles....take it as seriously as a class at school. Read up. It's okay to ask the meatheads at the gym, or other guys here for their opinions...but you won't be able to understand their advice, and sort through it and make sense of it if you don't even know the basics.
2) to add to chucky's advice that "each muscle contracts or it doesnt" :
When you're doing a particular lift, which muscle does it FEEL like you're using? That's a fundamental thing to ponder. Of course, sometimes newbies will feel the wrong muscle. For example, I've had a guy claim that he felt the shoulders burn during a cable pressdown variation (which should target the triceps, not shoulders). There could be many reasons for that (maybe his shoulders were sore from the previous day? maybe he wasn't holding the rope/cable correctly?).
But my point is: if you're unsure what a machine does, it should have a label on it, containing the machine's name, and a description (often illustrated) of which muscles it targets (as chucky pointed out). And when you're actually using that machine, make sure that the intended muscle is actually CONTRACTING. Don't focus on the weight moving. Focus on the intended muscle WORKING. Pretty simple advice, but trust me, it's advice often not followed. You'll see guys at the gym doing "dumbbell curls", but they focus on raising the weight, rather than CONTRACTING the bicep...and so they throw the weight, using momentum to raise it, instead of working the muscle. Defeats the purpose of lifting.
I disagree with sportsjockla on free weights being "more advanced" and machines for "newbies". Both experienced lifters and newbies benefit from both free weights and machines. Each has its benefit regardless of your experience level.
seafrontbloke saidWhilst arms and chest look good with a white t shirt, don't forget your legs. Chicken legs aren't a good look.
To add to this:
Chest and biceps alone won't make you look good in a t-shirt. A guy with chest and biceps, but no traps looks ridiculously awkward. Lats are also VERY important, unless you want to awkwardly look developed from the front and undeveloped from the back. And, of course, triceps. Without a pair of developed triceps, your biceps will look awkward. The tricep is, after all, 2/3 of your upper arm. The bicep is that nice bulge on the front side of your arm, but a developed tricep will make your arm look like a REAL arm, nice and meaty.