My mom said blends mango, then cooks it, squeezes in 1 lemon, add sugar and agar-agar powder. Try to taste it, if you like the taste then it's fine. Put in jar, then keep in fridge. (Sorry, my mom's recipe is very rough lol)
It depends on how sour you want the jam to be. My mom blends half pot of mango with 1 lemon. I guess the types of mango depends on your preference/taste. My mom generally uses sweet mango.
Good luck Joey! Hope you made it successfully! Sorry that my mom's recipe wasn't very accurate, cause she never really measure lol! She goes by agak-agak only haha!