To me the easiest way to add a blog page to a theme that doesn't have one is:
1) create a WP page that has a page slug of blog - you can title it Blog or anything else
2) go to Admin / Settings / Reading
select A Static Page
leave Front Page alone, even if its not set
set Posts Page to the page Blog you created
then you have a posts page.
Be aware that StudioPress themes use certain categories for home page sections. You will have to add a query_posts line to the themes's index.php page, before the WordPress loop, and exclude the categories that are displayed on the home page.
Another way you could handle it, rather than excluding homepage categories: if you are going to have categories that apply only to blog posts, create a category called Blog. Then create your blog categories as children of the root category called Blog. Then your query_posts can include only the blog category, which will also includes its child categories.
If the blog category is 16, the code would look like this:
<?php $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
that goes before the WP loop which typically starts with this
<?php if (have_posts()) : ?>
<?php while (have_posts()) : the_post(); ?>
The code about paged is necessary for the next page / prev page links at the bottom of the blog page to work correctly.