how to link to sections in the same page? How to create menu items with links that link to the same page (like scroll down further)?

Example: http://eshbeata.com/ , clicking on "Work" or "About" just scrolls down the same page.
This isn't so much a Drupal thing as an html link thing.

As you can see from the URL when you click on one of those links, you'll notice that they look like this:

http://eshbeata.com/#about 


or

http://eshbeata.com/#works


Note the hash tag and word at the end (#about and #works).  

That's called an 'anchor' and is essentially a link to a specific part of a page rather than a link to just the page.

Using anchors requires a two-part setup:


First you have to label the place you want to jump TO with your link.  So, by the exact place in the page that's the 'works' section, the author of that page would have the following:

&lt;a href="#" name="works"&gt;&lt;/a&gt;



It's just an empty link that names this spot in the page with the name 'works', and that's precisely what the link below will look for


Second, in the link "Work" in the top menu, there is the anchor '#works' at the end of the link.  

&lt;a href="#works"&gt;Work&lt;/a&gt;



Hope this helps.  You can read much more about this online just by searching for something like 'html anchors' or similar terms.