How does the earth's orbit affect global warming?
Hardly at all if any.
The Earth's orbit has its biggest impact on seasons, especially in the Northern hemisphere. During winter in the northern hemisphere, the Earth is tilted away from the sun and this hemisphere receives more indirect solar energy compared to the summer position. Consequently, the northern hemisphere is colder in winter and snow moves down to lower latitudes.
But this has nothing to do with longer term global warming.
Having said that, thousand year variations in the Earth's orbit due to Milankovitch cycles could eventually push the Earth into another ice age. But the current human-induced global warming has made this very unlikely, at least for the next 1,000 years or more.