Environmental groups will march to tell the world they think some WTO trade policies harm our environment and endanger animals. The marchers have pledged a peaceful, fun and non-violent protest. People around the world march to protest ideas and policies. Drivers have traffic cops. Campers have park rangers.
Kids have parents.
For almost everything we do, there are rules, and there are people who enforce the rules. It's no different with international trade. The first thing the WTO does is make the two countries talk to each other and try to solve their disagreements. If they still disagree three months later, representatives from the arguing countries go to the WTO and present their arguments to a panel of three people from other countries who listen, think and recommend a solution. WTO's trade rules are really pretty simple.