Each person has their own method. Some of the members have a bare
bottom tank(no gravel), some have a very small type gravel(see pic
i've enclosed), and some use big pebbles in the 3-5 cm range. Or you
can use colored glass beads 2-3 cm. Color is another personal choice.
Black seems to be the color for the moment, espcially if your doing a
planted tank. The white color most people have found shows algea and
gunk too easily.
The cloudiness in your tank may be due to it is in the cycling process.
Their is a link on the right hand side of the board in the main forum area
that explains how it works, but I'll give a quick explaining. Fish poop
produces ammonia, after 10 or so days bacteria turns it into nitrIte,
after another 10 or so days bacteria turns it into nitrAte. In a fully
cycled tank ammonia and nitrItes should read 0 in a water test. While
nitrAtes should read 5-20ppm. While your tank is cycling, you'll need to
do water changes to avoid the ammonia and nitrItes from becoming
poisonous to your fish. Once your tank has cycled, the cloudiness will
magically disapear.
Hope this helped a little. Feel free to ask anymore questions if needed.
Here's the link for cycling a tank:
http://www.kokosgoldfish.com/cycle.html