you will need both 7zip and blender for this and a program to edit images like paint .net or photoshop!

once you have downloaded and installed both 7zip and blender you can begin.
to begin you first need to go where farsky is installed. it is located at: program files (x86)/steam/steamapps/common/farsky once there you will see this:



then go to farsky.jar and right click and go to open with then open it with 7zip so when it opens it should look like this:

now go into the folder called res and then click extract then i recommend you to make a folder in the game directory like i did called mod stuff or something like that and thats where you want to extract it to!
now you have extracted the texture files and model files!

now that you have extracted the game files you can start to edit them!
now open the folder called res then open obj now go to what ever folder of the item you want to edit!

for editing the textures:
now that you are in the folder of the items texture that you want to edit (im using the hands for this example)
in that folder there should be a .png file with the name of the item you want to edit or there can be multiple but go to the one you want to edit and open what ever program you use for image editing and do your edits! (i used paint .net and i already edited the file)
now save that image once your done!

now i hope you remember the steps from before because you need to open the same .jar file with 7zip and go to the folder of the items texture that you edited:
ok once you are there delete the original file and replace it with your new file by dragging it into the folder (make sure your file has the same name as the original!! now you are free to close 7zip and open up your game and your texture should be your edited one:

so editing the file was not enough?? well heres how to edit the models!
so you need to go to the folder that you extracted from the .jar file and go to the folder of the items model that you want to edit and you will see a or multiple .obj files what you will need to do is open those .obj files in blender. how you open the .obj files is not as easy as just opening them you have to first open blender then go to files and click import and then click wavefront:
now you will need to go to the destination of the .obj file that you want to edit:


now open the .obj so it should look like this (mine has some edits):

now once you have done your edits on the model and you are happy with them go to export and click wavefont:


now you have saved the file now what you want to do is now that you have edited the file is open the same .jar file and go to the same folder as the one in the extracted one and delete the old file and drag and drop the new model file in and now you can exit out of it and open your game now your edited model should show up in game:

alot of the people that have been playing this game have been talking about modding the game and or editing the models to create there own fish or what ever and i got to messing about and trying to find out where the game files where located and it so happend i found them now hopefully we can see some great mods/texture packs for this game!!
i also apologise if anything is confusing in this guide this is my first one. :)