Converting old scripts to NPCs sripts?

[JkWhoSaysNi]

I'm trying to convert the default walk in a rectangle NPC script to work on an NPC server but i dont know where to begin

What do I need to change to get it to work on an NPCs? Are there any tutorials on this anywhere?

I found out i can add clientside at the top to make it clientside, but doesnt this mean every client could potentially see different things? I'm implementing random in the script so that it isnt always a the same sized rectangle. Will random calculate differently on each client?

If so, how can i make it run server side so all the clients see the same?

Thanks.