https://www.warhammer-community.com/201 ... ge-post-4/
That's the link you'll need to download the rules for kill team builds and mini campaigns and what not, but you'll be better off buying the new rule book off of GW so you can get all the teams in a hard copy, plus you'll get the full ruleset and art. The game is just more intense and narrative based than standard 40k games IMO.
Play some and let me know how it goes! I'll be posting some conversions of my kill team soon! Come take a look at some of my battlesuit stuff anytime!