1. On the navigation bar there's a shop button you can click that can take you there. Or just click this:
http://www.belltreeforums.com/vbshop.php
2.You can make a blog entry by going to your profile and on the left there will be a View Blog Entries link. Click that and it will take you to your blog. When you're there, look to the top right and there will be a create post button! There's also a Blog Tree button on the navigation bar. Same thing though, the create post button is in the top right.
You can change it anytime you want if you have enough bells to pay for it in the shop.