Filter posts by author selected in page

You can write your own query to include or exclude posts from an Author,
This page has documentation about the options you can pass to a query. http://codex.wordpress.org/Class_Reference/WP_Query#Author_Parameters

Here is an example to only get posts from the user $author.

$author_query = new WP_Query('author_name=".$author);

for user “Amin’ : 🙂

$author_query = new WP_Query('author_name=Amin');