Expression Web offers a Code Snippets panel where you can store bits of code (both HTML and CSS) that you might use over and over again. It's very handy and reduces much of the repetition of typing in the same code multiple times. You can find additional information in the Expression Web Help files. Go to Help > User Guide. Type in the keywords "code snippets" into the index search box and your topics will appear.
The image above highlights two blocks side by side, three blocks side by side, and four blocks side by side.
You can access the Snippets panel by going to Panels > Snippets. I keep mine docked on the left side of my screen.
Since more than one class can be applied to an element, the "alpha" class removes the left margin on the first block. The "omega" class removes the right margin on the last block.
The last div with the "clear small" class makes sure that any content added below the blocks will fall below the longest block.
Same concept, just with four boxes.