it's easier than you think!!!! i make mine with about two cups of fresh basil leaves, and maybe 1/2 cup of fresh spinach leaves,this more for the nutrition than flavor)..
in a blender combine a few garlic cloves, basil/spinach leaves, 2 TBSB pine nuts (i only use 1 tbsp), about 1-2 TBSP of parmesan cheese, and stream in EVOO until the consitancy that you want
Pesto can be super fatty if you don't watch your amounts, so adjust as needed for your program. i lean towards MORE green, less pine nuts, and just enough EVOO, then i add a little water too to help thin it...