#1 As far as the "how" - On the 2nd and 3rd, when we shut down the Port of Oakland for 24 hours, we did it by building a barricade with stolen chain link fences, stolen dumpsters turned on their sides, pallets, and people. This was accomplished at thoroughfare intersections distal to the border of the port. The march actually went in, but our barricades were not inside the border of the port.
#2 This is all very much illegal. It's called "civil disobedience." Jesus (basically) invented it, and people like Thomas Jefferson, Henry D. Thoreau, the BOSTON Tea Party (1773), and Mohandas Ghandi refined it before
Gene Sharp got ahold of it and gave us the keys to our own salvation with his lectures - but more importantly his book
From Dictatorship To Democracy. You might want to look it up.