Hope I understand your question correctly.
Many/most of the themes have a navigation bar built in. Typically, the Nav bar populates itself when you add a page (when your logged in, your main page offers you the choice of "Edit" or "Add Page")
If your theme doesn't have a Navigation bar area, you can enter edit mode, add a block to the header area and select "Auto Nav" from the available block choices. If you've purchased and installed other navigation add-ons (like Superfish) choose them instead.
Once again, the newly created pages will display on your nav bar unless you specifically check off the "Exclude from Navigation" option.

You can also add pages from the dashboards sitemap tab. Click on Home and select add page. This will also auto populate the Navigation bar and may be easier if you are adding several pages right away.

any reason why the page is not available after I have added it and even changed some things (logo) etc..

when I click on the nav bar, the page is empty and reads "no input file specificed". I have pretty urls turned on.

I turned pretty urls off, and now it goes to a host specific message that this page is not publised..

See these threads for some solutions to the "no input file specified" problem:
http://www.concrete5.org/index.php?cID=5346...
http://www.concrete5.org/community/forums/installation/solved-andqu...
http://www.concrete5.org/community/forums/installation/no-input-fil...
http://www.concrete5.org/community/forums/usage/andquotno_input_fil...