change code in WP login

Hi can anyone please advise me how the HTML coding for WordPress log in can be changed. At the moment when I log in I am taken to a 404 error page on my site not the dashboard when I normally login into wp-admin. The login URL that it tries to access is https://eac.eu.com/newsite/https://eac.eu.com/newsite/wp-admin/https://eac.eu.com/newsite/

When I look at the source code for the log in I can see the error.
I have copied the portion of the source code below

<p class="forgetmenot"><label for="rememberme"><input name="rememberme" type="checkbox" id="rememberme" value="forever"  /> Remember Me</label></p>
	<p class="submit">
		<input type="submit" name="wp-submit" id="wp-submit" class="button button-primary button-large" value="Log In" />
		<input type="hidden" name="redirect_to" value="https://eac.eu.com/newsite/https://eac.eu.com/newsite/wp-admin/" />
		<input type="hidden" name="testcookie" value="1" />

I need to correct this source code can anyone please tell me how this can be done.

thanks