.htaccess file problem

I am trying to install multisite. I followed all of the steps and when I tried to login again I got an Internal Server Error.

I believe that it’s the .htaccess file. It wasn’t there when I installed WordPress initially. I just created one and put the code for multisite in it. When I deleted the code and resaved the file I was able to bring up WordPress again. I’m not sure what’s going on there.

I can see the Network Admin dashboard so I’m confused.

This is the code I have in the .htaccess file:

RewriteEngine On
RewriteBase /Wordpress/
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule  ^[_0-9a-zA-Z-]+/(wp-(content|admin|includes).*) $1 [L]
RewriteRule  ^[_0-9a-zA-Z-]+/(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

Thanks!!
Dawn