Why and how did Kaiser Wilhelm try to get France and Britain into conflict in 1904?
I wonder if you are actually referring here to the First Moroccan Crisis of 1905 and 1906. So far as I am aware, there was no major attempt in 1904 by the Kaiser to drive France and Britain apart. Instead, he started to make such attempts in 1905 because France and Britain had formed the Entente Cordiale.
The Kaiser tried to cause a conflict by interfering in the French territory of Morocco. Specifically, he called for the independence of that country. He hoped that, by doing so, he hoped to get the British to take sides against the French, thus showing how weak their alliance really was.
The reason for this was that the Kaiser was starting to feel encircled. He was afraid that the major powers of Europe (France, Britain, and Russia) were going to create an alliance meant to guard against German expansion.
So, Wilhelm caused this conflict in an attempt to break up what he saw as an anti-German alliance.