MiwoEvents is easily installed as any WordPress plugin. That should be done through your site's backend.
Once you log in, you should open the Plugins => Add New => Upload section and click on the [Browse..] button in the Upload Package File section. Navigate to the same MiwoEvents file you have downloaded earlier and select it. Then click on the [Upload File & Install] button to start the installation. It will install :
1. The main MiwoEvents plugin
2. Front-end categories, events, locations and mini calendar modules
3. Language files
4. Database tables (#__miwoevents_attenders, #__miwoevents_attenders_group, #__miwoevents_categories, #__miwoevents_countries, #__miwoevents_events, #__miwoevents_event_categories, #__miwoevents_fields, #__miwoevents_locations)