Assigning class

Xoso: Your question doesn't really relate to the Block Class module, but since I understand how complicated CSS can be, I'll try to send you in the right direction.

Anything that stands alone or is followed by a period or hash mark is an "element" (div, img, etc.). Anything preceded by a period is a "class" (.block above).

To select an element within an element, you simply put them all together in a line:

div img {
  margin: 10px;
  }

This means "any image within a div should have a margin of 10 pixels."

To select an element within a particular class of block, add a .class to the outer element:

div.foo img {
  margin: 10px;
  }

This means "any image within a div of class 'foo' should have a margin of 10 pixels."

To select particular elements within a block -- blocks usually have class "block" assigned to one of their outer divs -- you'd do something like this:

div.block img {
  margin: 10px;
  }

I hope this gets you on the right track. Please refer to the many basic CSS guides found online for for help.