.htaccess链接到root

I am using FTP to upload a codeigniter website to a server. I have arranged the files in FTP as following (I don't have 10 in reputition):

The index.php finds the system and application folder. But I don't know what to do with the .htaccess file. I have tried various examples from the web and here's an example:

RewriteEngine on  
RewriteCond %{HTTP_HOST} ^(www.)?example.com$ 
RewriteCond %{REQUEST_URI} !^/public_html/ 
RewriteCond %{REQUEST_FILENAME} !-f 
RewriteCond %{REQUEST_FILENAME} !-d 
RewriteRule ^(.*)$ /public_html/$1  
RewriteCond %{HTTP_HOST} ^(www.)?example.com$ 
RewriteRule ^(/)?$ public_html/index.php [L]

This is the first time I use codeigniter and this question is probably stupid (sorry). I'm really thankful for all the help I can get.

I have another .htaccess file now which removes index.php from url:

RewriteEngine On
RewriteBase /example.com/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?/$1 [L]

If you want to remove index.php from urls then please use following code in .htaccess

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L]

Copied from revision 3 of the question

So the problem wasn't the .htaccess! I fixed it by making my controllers first letter a capital letter.