Making custom texturesEdit
Accessing the games texturesEdit
If you want to make sure your new textures line up with characters and blocks in the game, or match existing colour palettes then it's a good idea to use existing images as a template. You can get them by using this free tool by DontCare4Free and following the instructions included in the download.
Making your own texturesEdit
To make textures you'll need a graphics program that supports transparency for .png files. MS Paint doesn't have this but there's a very capable free editor called Paint.Net that does. Or if you are comfortable with another program use that.
Open up a game texture in your chosen program that looks similar to what you want to make and use it as a template, make sure areas that should be transparent are transparent and not just white and save as/ export a png with transparency to your Item, Tile or NPC folder. It should have the same name as the Item, Tile or NPC you are designing it for and the Item, Tile or NPC should have it's Type attribute set to -1 (in most cases).
be sure to have enough sprites in 1 file for the animation!
(the (int) useAnimation .ini attribute lets the NPC copy an animation of an existing npc,
not many pepople know this...)
With that you're set!
XNB Exporter by DontCare4Free
Paint.Net a really good (and totally free) graphics program which supports transparency in .pngs (unlike MS Paint)