hey i want to know how i can trigger a dropship to land in a sp mission what do i need to do and what do i script ?

Putting (help me) in the topic name is not going to help you much, as it makes you sound like you are demanding it. Because I'm in a good mood, I'll explain this.

There are two methods for dropship animations and actions. One is to use Bungie's existing recorded animations and script them just right while praying for a chance of success. The other is to create the animations yourself in 3ds Max, world-relative. Both methods need scripting. The recorded method is clunky but enables smooth transitions and hovering. The animation method allows you to decide what it looks like and how it acts, but you cannot hover indefinitely and if not done right, animations can be jumpy when switching. You must decide.