multiple errors: Special characters must be escaped

I guarantee the latest Dreamweaver CC did not create this code. 

Where did it come from?

Which version of Dreamweaver are you using?

Suggest you start over after reading chapters and doing some code exercises.

HTML tutorials - https://www.w3schools.com/html/

CSS tutorials - https://www.w3schools.com/css/

<h1 id="ebs"><font><font size="10";color=#002F5F><b>SITE 1</b></font></h1>

So many things incorrect, here.  As has been pointed out, font tag is obsolete.  Same for <b>.  Just say "NO".

Use CSS and the "ebs" ID for formatting.

<style>
#ebs{color:#002F5F; font-weight: bold;} /*font size can be set here, too */
</style>

<h1 id="ebs">SITE 1</h1>

The following is nowhere near valid:

<a> <a href id"seitenanfang" style="color:darkslategrey;text-decoration: none">

The best thing for this:

<a href="{A URL GOES HERE}" id="seitenanfang" style="color:darkslategrey;text-decoration: none">

But, again, use the ID and CSS style to format it.

As Jon Fritz stated, you have much to learn before getting elbow-deep in coding.  Fundamentals are paramount.

Best of luck in your endeavors.

V/r,

^ _ ^

<h1 id="ebs"><font><font size="10";color=#002F5F><b>SITE 1</b></font></h1>

1. The font tag is obsolete

2. There is an unclosed FONT element

<a> <a href id"seitenanfang" style="color:darkslategrey;text-decoration: none"><p><font size="2"><center>zum Seitenanfang</center></font></p></a>
	</footer><footer></footer><h1 id="SEITE2"><font size="10" color="#002F5F"><b>SEITE2</b></font></h1><footer>

 There are 7 errors in just this small sample of code

1. href ????

2. id"seitenanfang" ????

3. font element obsolete

4. center element obsolete

5. unclosed a element

6. stray footer end tag

7. unclosed footer element

I give up checking the rest