As long as you tighten your saddle snugly after adjusting it you can't do anything unsafe. Yes, the curvy thing has ridges (probably) on it so that you can adjust the tilt of your saddle. Loosen the bolt that holds your saddle to your seatpost until you can wiggle the saddle around a little, settle it horisontally and tighten the bolt again. Testride and redo if necessary 
As you're loosening the bolt check if it goes through a nut on the other side, you might have to hold onto this nut to get it tightened again.
If you find yourself pushing yourself back on the saddle anyway, to get further back "behind the pedals", you might want to try moving the saddle back a little as well. Loosen the bolt, slide saddle back a bit along the rails, re-tighten.
If you have trouble, post a picture and we can help!
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett