Before you can post here, make sure that you have a MySteinberg user account. Once you have created your MySteinberg user account, you have to extend it by creating a forum profile. To do this, click on "Forum" (below "Support") on the left menu inside MySteinberg.
If you already have a MySteinberg account, creating your forum profile is all you need to do.
More details about creating an user account can be found here at MySteinberg.
Please also have a look at the forum FAQs.