Is performing Salatuj Zohr instead of salatul Jumuah would be counted as qaza? is it a major sin or not?

Question

If I go to the masjid and found that slatul jumuah has just been ended, then what should I do?

• Should I perform salatuj Zohr?
• Should I perform it as qaza?
• Would it be counted as major sin?

Note:

I might not pick the appropriate title before, so that people claimed it as duplicate. Now, I fixed the title.