Hello, I'm kinda new at WoW so i still don't know too much about the raids but i'm tired of making random heroics over and over.
What do I need to start tanking raids?
What are the easier raids that I should start tanking?
Any major gear upgrade?
You look like you're pretty well set to start tanking raids IMHO. If you find a good group, and with the 30% buff, you'd be right tanking at least first 4 of ICC 10. If you have a decent DPS set maybe try running ICC as DPS once or twice so that you can see the fights and get used to them - otherwise check out some videos. The first four bosses in ICC are actually quite easy, especially now since the 30% buff. I'd say more pugs would trip up on ToC now than ICC. If you just want to get a feel for tanking a raid maybe run Naxx for fun?
In terms of gear it looks ok to me. There are probably a few upgrades that you could still get from farming the normal and heroic ICC 5 mans and the TOC 5man - if you are tired of grinding emblems for the T9 gear (which I totally understand if you're bored running randoms).
Swapping the pants for the T9 pants would be a good start, or you could try for Legplates of Frozen Granite from normal FoS (you can farm the normals as much as you like/can stand :P)
Try and grab The Black Heart from normal ToC (to replace gossamer). Black Heart is one of those trinkets that you'll probably hang on to for a while so it's worth the time getting IMHO.
You could potentially replace the blue ring with Signet of the Impregnable Fortress which you can get with emblems. Wouldn't stress too much cause you'll only end up replacing it with the Ashen Verdict rep ring anyway.
You should look at replacing your weapon as soon as you can. Mourning Malice is ok if you want to farm normal HoR. It's got a lot of expertise on it so it may bring you closer to the cap (you're currently under). The axe from H PoS would be an upgrade as well. I've also seen DK tanks recommend the Orca Hunters harpoon from H HoR (it has a blue socket which is handy).