hardening wordpress

Hello all,
My theme is Tienda basic

I would like to lock down our site’s sensitive directories via FTP.
Have read the Codex about writing files by the user acct.

I know where the files are and would like to change them to secure our sites. These are the files I have to change but how????
The root directory
wp-admin
wp-includes
wp-content

Have read this in the codex, but am perplexed on how to do this all.
thank you for any help
K
File Permissions

Some neat features of WordPress come from allowing various files to be writable by the web server. However, allowing write access to your files is potentially dangerous, particularly in a shared hosting environment.

It is best to lock down your file permissions as much as possible and to loosen those restrictions on the occasions that you need to allow write access, or to create specific folders with less restrictions for the purpose of doing things like uploading files.

Here is one possible permission scheme.

All files should be owned by your user account, and should be writable by you. Any file that needs write access from WordPress should be writable by the web server, if your hosting set up requires it, that may mean those files need to be group-owned by the user account used by the web server process.

/
The root WordPress directory: all files should be writable only by your user account, except .htaccess if you want WordPress to automatically generate rewrite rules for you.