Within 15 days of the date the office gave you that ticket, you need to return it to the clerk's office with box three on the back checked, so you can request a contested hearing. The clerk's office will set a hearing date and time. Your hearing date probably won;t be for a few months from now, so prepare for your hearing by writing down - RIGHT NOW - what happened so the recent events are recorded and fresh in your mind. Then go to the hearing and read off your version of events. Be sure to tell the judge that you are reading something that you prepared right after the incident. Give the judge all the details and speak with clarity and honesty. Fighting your ticket in this manner is all that an honest person can do. Far too often we as citizens back down when we should be fighting for our freedom.
I agree with the other attorney that you need to request a contested hearing by checking the appropriate box on the back of the citation. I also agree you should write down your recollection of the events and talk to any witnesses (ie passengers) if there were any.
In Spokane, sometimes these hearings are only a few weeks away, other times longer. Depending on what your traffic record is like, there may be other options available to you. If a "committed" finding by a Judge will impact your insurance or your employment, you should contact an attorney.