Mr. Hill is correct. Do it all at the same time. Follow up and make sure it is received. Things tend to get lost or buried with government bureaucracies. You may want to send it certified so you have proof of the mailing date and a receipt for your records should they claim not having received it. Good luck. Hope this helps? You are always better off with a lawyer!!!
If you are going to plea by written declaration you should also send in any applicable forms and the bail amount. Are you doing your trial by written declaration as well? You really should consider contacting an attorney to assist you. There are many viable defenses to speeding tickets and a local attorney would know how best to argue the facts of your case. Just contact a couple attorneys from AVVO to see what they can offer. Many have free consultations.