Hiya! So I want to make a really cool halloween themed farm, I know how to edit images and recolor and stuff, I just need someone to help me put them in the game, IE you send me the images, I edit them, you code them into the game? Please help let me know if you're interested
Just replacing the graphics of the game requires absolutely no coding actually. You just have to be able to unpack and repack XNB's, http://stardewvalleywiki.com/Modding:Creating_an_XNB_mod#First-time_setup You can learn how to do that on that wiki.
That same page on that link will tell you how to edit maps. Your map file is within Content-> Maps -> And then will be named depending on which version of the map you have. The default is called Farm.XNB, the foraging map is Farm_Foraging.xnb, and the others are labelled similarly
I suggest reading all of that page I linked, It's too much to explain here especially when someone else has already explained it all. In short, you don't paint the map, you paint tiles that are used to create a map in a program called TiDE.