I would like to add a link on my template to link to the users own blog posts the code i have tried using is <li><a href="?author=<?php the_author_ID(); ?>">test</a></li>.
Edit, had a typo on the code on here and the url that it takes you to is just ?author=
Its very simple.
you can use wordpress user list plugins instead of writing codes.
Did you mean you want to print number only in the URL. just echo the_author_ID().
<li><a href="?author=<?php echo the_author_ID(); ?>">test</a></li>