I am not the author of this plugin, but :
This plugin works with something that is called a SHORTCODE.
since it appears that this plugin does not provide a widget , and assuming you have almost no programming experiance in wordpress, you can do one of the following :
1 – You need to put the shortcode [front-end-upload] inside a post or page . just copy and paste (with the square brackets) . there is no need to be affraid of nothing . In this case the upload “form” will be displayed in the specific post (or page ) where you have pasted it . you can also add normal text like any other post / page .
2 – If you really want it to appear inside a WIDGET , you will need to enable SHORTCODE execution in your widgets, and then paste the SHORTCODE ( [front-end-upload] – remember ?? ) Inside a TXT widget .
Now , in order to be able to do that option, you can either :
A – use another plugin for shortcode execution , like this one :
http://wordpress.org/extend/plugins/shortcodes-in-sidebar-widgets/
B – copy the following code , and paste it inside your theme file that is called functions.php .
add_filter( 'widget_text', 'shortcode_unautop');
add_filter( 'widget_text', 'do_shortcode');
This code will enable you to use shortcode inside any normal text widget. (I never really looked , but I guess these two lines is more or less what that plugin from the previous option is doing .It is that simple.)
Krembo99, thank you very much for your clear and informative answer. I got the plugin to work because of your instructions.