Hello Valeriy

Please access https://dev.twitter.com/ and you can use belows instruction as your guide:

1. Edit your Twitter application. If you didn't create any apps, please create one.
2. Check website URL, Calback URL make sure they are the same as your site domain (http://www.yoursite.com and http://yoursite.com make a big difference)
3. Check if the Access level is Read and Write
4. Check if "Allow this application to be used to Sign in with Twitter" is ticked under Settings
5. Go to the EasyDiscuss -> Autoposting -> Twitter autoposting. Just follow the steps.

If you encounter problems or have anymore question, please don't hesitate to ask us.
Please be advise.
Thanks.