Load content into external page

Ok this is what I need, I hope someone can help me..
I have website that uses php to load the content dynamicaly into se site, one of the pages is tutorials.php, and what I need is to load all the content from the wordpress database under that category into that page. My word press is located in separeted directory.
this is how my site looks.

/
includes/
blog/ (which happens to be whe word press root directory)
index.php
contact.php
tutorials.php (here is where I want to load he tutorials category from wp.)

I have managed to load all the post into index.php but it just loads everything. I don’t know how to build a query that loads the content from an specific category because they are all 0 (cero) in the post table.
Im looking to build a query like this:

SELECT * FROM wp_post_table WHERE category_id = "tutorials_category" ;

Anyone can help? thanks for taking the time to read this topic.