Start Evolution by pressing Applications → Internet → Evolution Mail.

Press File → Import... to start the Evolution Import Assistant. Then, press Forward.

Select Import a single file and then press Forward.

Press Browse..., locate the file which you saved your calendar into and select it. Press Open.

From File type, select vCalendar files (.vcf), iCalendar files (.ics) or Outlook CSV or Tab (.csv, .tab), depending on which format you saved your calendar into. Press Forward.

Choose a location in which to save the calendar, such as On This Computer → Personal. Ensure that Appointments and Meetings is selected and then press Forward.

Press Import to import the calendar into Evolution. Once importing has completed, the new calendar should be immediately available.