MijoEvents is easily installed as any Joomla component. That should be done through your site's backend.
Once you log in, you should open the Extensions => Install/Unistall section and click on the [Browse..] button in the Upload Package File section. Navigate to the same MijoEvents 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 MijoEvents component
2. Front-end categories, events, locations and mini calendar modules
3. Language files
4. Database tables (#__mijoevents_attenders, #__mijoevents_attenders_group, #__mijoevents_categories, #__mijoevents_countries, #__mijoevents_events, #__mijoevents_event_categories, #__mijoevents_fields, #__mijoevents_locations)