Copy the plugins you've downloaded to the folder blogs\plugins
Go to administration panel, then activate the plugin

http://manual.b2evolution.net/Plugin#Installing_a_plugin

Thanks but files will not upload as wrong file extensions and zipped file is over 1.0mb for weather file and unzipped sections in German plugin are html not valid file extensions for uploads
I am mystified when these plugins are supposed to be made for b2 evolution
Can you help?

Check the version of the plugin. A 0.9.x plugin will not work in a 1.8.x blog etc.
Unzip the download and upload a complete folder if there is a folder in the zip or upload individual files if there isn't.
The plugin should show up in the Back office

Regarding your second question about the contact.php: this is already in your blog. Search for "contact the Admin" probably in the footer. You can duplicate the code from skins/(yourskin)/_main.php and place it somewhere else.

Good luck