[TYPO3-windows] Please need help

[insi insi]

Hii..

I need your help but not sure whether or not is the appropriate place, 
forgive me if it is wrong, could you please direct me to the right person or 
forum? I couldn't find this forum for help/assistance.

I am new in this and a little bit background in website development.

I am using this as locally not connecting to the server only start apache 
and mysql on my pc.

I have the following questions:

1. I would like to change the username of root and password, how can I 
change it or is it possible?
By the way, what is the default root password?

2. Last week I created a new database but now, I cannot change to this new 
database. Do I need to go online internet in order to connect? because I am 
in offline when trying to connect to this new database.
If I need to go online, is it possible to connect or modify in offline mode?

3. In the modern template building part 1 note page 27, where can I find 
Extension Manager to import extension from online repository?

Thank you for your help.

Iwan