“Cross the bridge and begin the search for Crota's Death Ceremony.”
You will arrive in The Stills. You need to wait for a short while for the bridge to form. If you go before then, there is a chance you will simply fall to your death. Once the bridge is formed, you simply need to run through to the bright light. Head on through into it.
You will be cloaked and you now need to both avoid detection and not break the cloak. When you are running around, you will find you start to look red. This shows how close you are to breaking cloak. The visible you are, the closer you come to losing the cloaking. If this happens, not only do you have a massive swarm of Hive to deal with, but you have the debuff Exhausted. This greatly reduces your jump and stops you from running until it wear off.
You will see also see a Red barrier appear around Hive in this area. This shows their detection radius. If you step inside here, your cloak will break.