Insert 'Add Media' to my posts and pages for visitors to upload images etc to my

You must create a upload process. Recently I used this project to do it:

https://github.com/valums/file-uploader/tree/2.1.2

Here is my code:

https://gist.github.com/4387872

Uh! I am too dumb for that complicated stuff, all I would like to do is activate a WP plugin and have the upload button on my page where I choose. Thanks for your response and kind help
Regards, Ivan

I dont know of any plugins that provide this ‘out of the box’, but check out gravity forms. It is very straightforward to set up & you should be able to easily create a form to allow uploads.