For bricks, first open notepad (or anything similar), then make something like this:
1 2 3
BRICK
Then save it and call it 1x2.blb (or for your brick,
BrickName.blb)

The 1 represents a number of studs. The 2 is similar to the 1, but in the other direction. The 3 is the height in plates, or how many plates stacked up on each other it would take to reach the top.
Now we turn to server.cs:
datablock fxDTSBrickData (brick1x2x3Data)
{
brickFile = "./1x2.blb" ;
category = "Bricks" ;
subCategory = "1x" ;
uiName = "1x2" ;
iconName = "1x2Brick.PNG" ;
};or if you would like to know what goes where, this might help more:
datablock fxDTSBrickData (brick[Name]Data)
{
brickFile = "[.blb file]" ;
category = "[what tab on the top it should be in" ;
subCategory = "[sub category such as "Prints"]" ;
uiName = "[name]" ;
iconName = "[.PNG image of the brick]" ;
};(replace [ ] with what you have that corresponds)
To make the PNG image, take a snap shot of the brick (or bricks, by them selves) in construct. (But you must first make it (or them) work in Blockland, so leave out the
iconName = "blah"; till you finish the rest of the addon.) Make sure the .PNG is 96x96. The easiest way to do this is to use gimp:
http://www.gimp.org/If you have several bricks you'd like to make, the make several .blb's, then in the server.cs, make several data blocks(one for every brick).
Then add the description.txt (description goes here)
Finally, make a zip (use winzip for Windows, zip in Linux console, ? for Mac) containing the .blb(s), server.cs, description.txt, and the .PNG(s) (not till you get the screen shot (see above)) and call it Brick_[what ever you like].zip (no spaces).
I hope you could under stand it.

Unfortunately, don't know how to make special bricks, so I'll leave to someone else.