There are multiple ways of using your PostLists...
First of all, you have to define the lists you like to use.
You can do this on this page:
Select "New List" under "PostLists Lists" and click the "Select" button.
Then type in a special word in the first field to use as placeholder.
For example you could use "MYPOSTLISTSEXAMPLE".
Use a word that does not occur anywhere else in your posts.
Continue configuring the list as you like, via the other fields.
Finally save this list configuration.
Now you can use this list:
Use it on pages or in posts:
If you like to insert a list in a page or a post,
just type in the placeholder in the content of you post/page exactly the same way you defined it (case sensitive).
For the example you would have to type in "MYPOSTLISTSEXAMPLE".
This placeholder will get replaced to the list, if you view the page/post after saving it.
Please note: If there are no posts in your list and you have not defined the string to display if there are now matching posts,
the empty list will not get displayed and the placeholder only gets removed from the output.
Use it as a sidebar widget:
Add a new text-widget to your sidebar.
Open the configuration of the new text-widget to edit the text.
Now type in your placeholder as text, the same way as it is explained for the usage in posts.
Use it in template files:
To add the list to a template file, you just have to call the function pl_postlist( $placeholder ) and pass the defined placeholder of your list as a string.
For the example you would have to add this code anywhere in your template file:
<?php
if( function_exists("pl_postlist") )
pl_postlist("MYPOSTLISTSEXAMPLE");
?>
The list will be displayed exactly at the position you added the code.
For further help, you can visit the plugin page. You will also find this help with screenshots in german language there.