These guys are pretty simple to make and the pictures should explain it all but I'm including text in case anything isn't clear.
Check out Step 6 for a video tutorial.
-16 2x4 bricks
-10 2x2 bricks
-1 technic pin that is half tube, half cross-rod (see the second picture for a close-up)
Step 2: Torso
Put a 2x2 in the middle to connect the 2x4s. Add 4 more 2x2s, one on each corner, to the bonded 2x4s.
Step 3: Limbs
Connect one limb to each of the 2x2s added to the corners in the last step.
Step 4: Connect 'Em
Cover each limb with another 2x4, it will line up with the 2x4 below it.
Step 5: Head
Stack two 2x4s on top of this going the other direction.
Put a 2x2 on the bottom layer, in the middle.
Stick a technic pin into the 2x2, tube side out.
Place the head onto the rest of the model and you're done. Enjoy playing with your Block Dude!