I was wodnering if someone could explain to me step - by - step how to blend render into the background?

Thx in advance ;)

I was wodnering if someone could explain to me step - by - step how to blend render into the background?

Thx in advance ;)
It's different for each render/background combo so you'll only get so far with generalities.

Gradients and photo filters would be the most efficient way.

Lighting > Gradients/Photo filters you can blend the color all you want but in the end if you have a shadow where your light source is that'll screw it up a whole lot more than a tint of color.