I've added the following code to one of my articles, but when I view the article I see that exact text so nothing is happening.

Code I'm using:

{arisexylightbox activeType="picasa" user="markoudev" album="Las Vegas"}{/arisexylightbox}

I've installed:
mod_arisexylightbox.zip
plg_system_arisexylightboxanywhere.zip

Need I more plugins or what is going on...?

Hello,

Check that "System - ARI Sexy Lightbox Anywhere" plugin is enabled and if you insert plugin code with help copy-paste method in a WYSIWYG editor, switch editor to plain text mode and insert code again because editor can add extra HTML code which can break correct plugin code or you can provide link to page where we can see this issue and temporary access to your Joomla! backend by email and we will investigate this issue.

Regards,
ARI Soft

SOLVED.

Regards,
ARI Soft