I am thinking about starting a new character in MW and I want too make an Imperial Crusader. I'm not sure how I should make the class, but I want too follow the prinsiple of the in-game decription of the Crusader class:
Any heavily armored warrior with spellcasting powers and a good cause may call himself a Crusader. Crusaders do well by doing good. They hunt monsters and villains, making themselves rich by plunder as they rid the world of evil.

Can anyone help with the character-build?

I'd try this:

Majors: Restoration, Destruction, Alchemy, Heavy Armor, Longblade

Minors: Enchant, Mercantile, Speechcraft, Armorer, Blunt or Marksman

Combat specialty with strength and endurance (for Lady sign) or agility (for Atronach)

Lady would be best sign except for the fact that an Imperial gets no magicka boost and you'll have a hard time using Destruction effectively so
maybe Atronach would better here. It's a pain to deal with but you'll have a sword and armor for fall back on if you run out of magicka and naturally, as a good
Imperial Cultist, you'll have an amulet of Divine intervention to get to a magicka filling altar.