sidebar not showing up at the right place

I need your precious help:

I want to create a sidebar on this site:
https://www.luxembourgartistsforhaiti.lu

It has a nav bar horizontally and the navigation are only pages:

I wanted to create a sidebar on the left, have already made some space to do so there but am not able to but the sidebar on the right place:

What I have done so far:

I put this code on the page.php (in comments for the moment)

<!-- <?php if ( !function_exists('dynamic_sidebar') ||
           !dynamic_sidebar('sidebar') ) : ?>
  <!-- This will be displayed if the sidebar is empty -->
<?php endif; ?> -->

And the navigation shows up over the title of the page :-/

In the style.css file I have put this code but it does not react at all!

/* SIDEBAR */
#sidebar {
	float:left;
        width:200px;
	padding-bottom: 100px;
	color: #231f20;
	padding-left: 30px;
	margin-top: 10px;

My question now is:

1. can someone help me out here please ??
2. Do I have to create a sidebar.php and what do I have to write down
3. The css code for the sidebar has to be nested somewhere else in the css code itself???

Hope someone will give me a hand here … it’s for a great cause and I am also not asking one cent for the job ??

Diana