You must think the whole document as a whole. There are some general principles, which in fact are common sense principles:
Don't crowd the graphical elements in a zone. Try to spread them all over the document. But don't spread them too much. Try to keep a balance between elements and the spaces between them. Not too crowdy, yet not too diluted. Symmetry is an important concept. As a general rule: use symmetry between the big zones and asymmetry for the details.
Don't be afraid to use colors. When there is not much content to fill the document, colors might cover the deficit. But don't use all the colors Use the colors grouped in "pallets" starting from a dominant (first) color. That means you must use related color in combinations which are pleasant to the human eye. There are many pallets, all of them created by using math relationship between colors. Here's an example:
Usually 3 colors/nuances are enough. Try to keep a good contrast balance. Unless you are making the site of a Circus, don't use altogether strong and complementary colors. Straight Red (ff0000) + Straight Green (00ff00) is a classical example of contrast which must be avoided.
Don't use too many font types. 3 types is usually too much. Use sans-serifed fonts for web. Give your fonts a certain size. Try to balance the size of the fonts: not too small, not too big.
The menu is very important. It must make a firm contrast with the other zones on the document. The menu should be the first thing the user must see at a first glance
Zones management, importance order
People which use left-to-right writing/reading cross the document with their eyes from top-left to bottom-right, and that the descending order of the importance: The most important things must be placed top and left, the less must be placed bottom and right.
So: SH100, your design is far from being professional, to say the least. Try to see on the web how did the others, as MrSnowDrop advised you