Your weight on the saddle should be mostly carried by your "sit bones", the bones that you sit on if you are seated on something hard like a wooden chair.
Make sure that your saddle is nearly level front-to-back. You can try adjusting the tilt slightly to see if that helps, and you can also slide it. Also make sure the height is good. Your knees should be just slightly bent at the bottom of the pedal stroke, not locked out. Most people have the saddle too low and don't get optimal efficiency.
The riding position depends on the kind of bike you have. A rule of thumb is that your back should be at about a 45 degree angle from vertical, and your elbows should be slightly bent. On a commuter/comfort bike, you will be a bit more upright (more pressure on your rear), and on a road bike you will be a bit more stretched out (more pressure on your wrists). You can adjust a bit by sliding the saddle on its rails, or changing the angle or height of the bars. You could also try a different stem if you need to adjust.
For frame size, I recommend checking to see if there's a size recommendation from the manufacturer. For example, a large frame might fit people 5'10 to 6'. You can probably up or down from the one that's recommended for you, but comfort might not be ideal if you go too far from your size.
The handlebars should be about as wide as your shoulders. It's easy to move the grips in a bit to see if that helps, but moving them out requires a wider bar.
You might want to look into getting a different saddle that fits you better. There are different widths and levels of padding. Sometimes a firmer saddle is better because then your weight is mostly on the sit bones instead of you sinking in and putting more pressure on softer areas.
If your wrists are sore it could be from bad riding position (see above) or just from shock from the road/trail. If you have a rigid fork, try riding on smoother roads for a while. If you have a suspension fork you might be able to adjust the preload so that it absorbs bumps better. You could also try padded gloves, but I find that they don't help and give me blisters. Softer grips might be more useful.
I'm not an expert in bike fit, but I don't think there are any one-size-fits-all recommendations since everyone's body is different. Don't be afraid to try adjusting things and see if the changes help or make things worse. If you don't know how make adjustments, look it up (there are lots of good resources online) or ask here.
It might help if you give us some more info, such as what bike do you have (including frame size), your height and weight, what kind of riding you are doing (roads, trails, sidewalks, or bike paths) and how far you are riding.
You could also post a picture of you on the bike from the side, if you don't mind putting pictures of yourself on the internet.
Finally, I'd like to add that you should stick with it! With some adjustments and some more time on the bike you should be able to ride pain-free.