Does anyone know anything about gardening?

I'm sorry, but you can't! The fact that it is fruiting so heavily and the trunk and main boughs appear to be more than a few years old is the giveaway. As was suggested upthread, your best bet is to remove the lower boughs currently weighed down with fruit. The best time to do this is after the leaves have fallen. If you can be arsed, remove about a third of the young fruit on the remaining boughs next year. This will leave more of the tree's energy to grow and the remaining fruit will be better quality.