The wildneress has undergone some significant changes recently - not least because you can't be attacked by other players anymore. To enter the Wilderness you simply need to click on the ditch to jump over it. When you click on the ditch you'll get a message warning you about the dangers of the Wilderness etc. You'll need to click on "Enter Wilderness" to get in. The main thing to be wary of apart from the dragons you are looking to face are the new Revenants, who can freeze you, teleblock you, do significant damage and if you want to fight back, they heal themselves as well. If you want to do some player killing, you have to do it within the confies of the Bounty Hunter arena. More details about what I've written can be found in the RuneScape Knowledge Base.