Hey, welcome to Mibba! It seems your friend has already started teaching you the basics of the site but you can still ask me anything if you need. Hope you enjoy it here
First we have the Knowledge Base, you can go there for almost all of your questions from posting stories and poems to navigating the blogs.
Next we have the forums, which is where I spend a lot of my time.
First off, you can introduce yourself in the Introduce Yourself forum! Obvious right? Just post a thread and you can easily make friends. If you post what you like in your introduction, people often make site recommendations, stories and contests and such.
Tips: is a writing tips forum, and it's so helpful. Whether you're looking for a writing prompt, a editor or even just a place to develop your characters, this place is perfect!