Joomla on readynas

Hi, First of all sorry for my bad english 

I'm using my nas RN104 only for storage and backup for my business and do not have any knowledge about programming etc.

My problem is that i want to create a new joomla website and hosting it in my nas.

I have done everything i could:

1. Install php
2. Install phpmyAdmin
3. Install Mysqlserver and finally
4. Install Joomla

Also i followed the instructions about enabling http and redirecting default web access to a folder i created with the name "mywebsite".

Everything seems to be ok but i missing something very important. The joomla files are not in the shared "mywebsite" folder and i don't know what to do

1. Do i have to install joomla in the specific folder and how?
2. Do i need to give web access to the folder where joomla files are located and how?

Also i do not have access to the folder where joomla files are, because i'm a newbie. 

Thank you in advance