Hello Britta,
With installation of “Landing pages” plugin in your WordPress website the new category named “landing-pages” was created.
You don’t have appropriate menu item on the left side in WordPress, because every existed “Post” and every new “Post” in your WordPress can be used as landing page. For this, you need only add your correspondent “Post” to “landing-pages” category.
After you have added your “Post” to the “landing-pages” category, you need to open this “post” for editing.
In “post” editing window you will see some of settings and variables specially for “landing pages”.
Note:
If you “post” was added to “landing-pages” category – it will be saved in WordPress like “Landing Page” and NOT LIKE “Post”.
Also you can read description about using of “Landing Pages” plugin at plugin description page.
Hope this helps, but if you have more questions, please contact us using email support(@]wpadm.com or contact form.
Landing Pages support