Okay the big thing they teach you in web design these days is the CSS box model:
http://www.w3schools.com/css/css_boxmodel.asp
Think of your page divided up into boxes that contain different sections of content. You can rearange these boxes around how ever you wish. These boxes are div tags in HTML, where you put in the content. Be sure to put the entire page in a it's on box-div as well. It is common to give this the wrapper or container class/id. Make sure you give this a width so the page doesn't infinitely streatch out in hug browser windows.
Typographical heiarchy is also important. What that means is you want headers of different inpotance to be of different size, more important ones are biggger, the less important ones are smaller, so use and style those h1-h6 tags wisely. Also make sure paragaphs don't stretch out too far, as it makes them hard to read.
And color, make sure you're color scheme isn't pukey. This is a good tool for color schemes:
http://paletton.com/#uid=1000u0kllllaFw0g0qFqFg0w0aF
Advanced tips that you may not care about:
Aso somwhat important, but not essential if you are jhust a begginner, think about how it looks on a wide variety of screens. Using relative measurements like percentages and ems can help you web pafe scale better. Using media queries helps with different devices as well, set really small devices to have a different box layout and it will look better, the most common practive is to stack all your boxes on top of one another.
Also:
Or the short easy way if you don't care about building design skills, there are frameworks like
bootstrap and
http://foundation.zurb.com/. They already give you some CSS styling to work with so you have a servicable layout on all viewing devices. They aren't newb tools though, you do need to already know how to do CSS to use them however, so I only recommend using them if you know how to write CSS, but suck at or are too lazy to worry about coming up with nice styles yourself. You definitely need to understand, classes, ids and inheritances at minimum to get any real use out of them.