How to update mac?

Question

macOS

Given
imac on core2duo
os x 10.7.5
2008 There is no Internet
in the volume
required for updating . I assume that there are some files for updating or a direct distribution kit, etc. Actually the question is that I'm not friends with the poppy yet and I don't know where to download and how to install , help with advice !?

Answer 1

download boot image (used to be on rutracker or nnm), boot into recovery mode and install)
something like this