Hover over your username, top right. That is your name in the top blue band.
In the drop down which appears, go down to "Your content", and click. This will allow you to see all of your postings.
Starting a new thread.
First, click the site title, and select which section you wish to post in

Windows support?)
View attachment 7672
Once in (Windows Support), you will see an item on the top right "Post New Thread"
Give it a title, write what you will and post.
One advice, of benefit to the forum. If your problem is solved, you, and only you, can then mark it as solved.
P.S. In defence of the forum. 90% of forums, today, are based on a common format "XenForo". I have used forums for many years, so perhaps that is in my favour, but, on observation, I find this one as easy to navigate as most. Some have introduced different layouts, which, particularly in one case I have experienced, can be very confusing to navigate.