On every contract screen, you can swipe to the left to see the Twitter feed associated with this contract.
If you also wish to post on the Twitter feed, you need to go to "Join this Conversation" and enter your Twitter credentials. If you don't have a Twitter account yet, you may create it there.
After connecting your account, you will be able to comment on each feed and also interact with the other users: Follow, Like, Mute, Reply, Retweet.
When you connect, and on Twitter settings, you will find the option to "Automatically post trades on twitter". If you have this setting ON, whenever you trade on iBroker, an automatic message will be posted to twitter by you with your trade details.
To disconnect your Twitter account from your iBroker, simply go to Twitter Settings, switch Twitter to OFF and Save.