three newbies questions about WP

1. when I enter to category URL the posts are shorts and I need to enter to the post to see the full post. how I change it that when ill enter to the URL of the category the posts will be full?
2. when I enter to the editor and change something it doesnt change anything and not save it. what's the problem? how I fix it?
3. I got 2 categories in the blog, and I want that only one will display on the homepage of the blog and not both of them and it someone wants to see posts of the category that not display on the homepage of the blog they will need to enter to it via the menu.

I hope you guys understand me because I got really poor english, sorry for that, and thanks!

1. You need to change <?php the_content(''); ?> to <?php excerpt(''); ?> in index.php or home.php
2. You need to hard code which category you need to show in index.php or home.php
3. Make menu with this category.

Hey! thanks for posting but how can i change the index.php or home.php if I told u on question number 2 that I cant change anything it doesn't save it/

and what is it hard code?

there is no "<?php the_content(''); ?> or <?php excerpt(''); ?>" on index.php and there is no home.php or I just don't know where is it.
about question number 2 I solved it. it was infected plugin.
please help me guys );

Thanks for the info