I don't know if this has been translated already (presumably not to Turkish but any hacker sourced translation will be useful in this), though I would not be surprised if it has. If it has then you can have a look to see what said hackers changed as part of it and then get some idea what will be necessary for you.
Generally you will need to find the location of the script, figure out the formatting of the script, alter any fonts to have any additional characters*, alter any pictures that have text on them (assuming you want to).
*looking up just now what the Turkish alphabet entails (basically normal Roman/English one plus Ç, Ş, Ğ, I, İ, Ö, Ü and minus Q, W and X) I would probably look at the European version of the ROM as French and German have a lot of those and you could probably adapt some others easily enough. If you are lucky then the game will use a NFTR font for the game and with that you can edit it fairly easily, if not then you get to figure out the font format.
As it is for the DS you do also get the option to explode the game into its component files (older cartridge based consoles don't have this option). Tinke, crystaltile2, ndstool and several other tools are available for this.
I do have a guide to DS hacking that covers a lot more. I don't think I have any links to any guides in Turkish (most systems are similar enough that if you understand say how to make a table from the perspective of a NES game it is much the same whether it is said NES, something from the 1970s or something released yesterday) but if you can find one then have a read.
Link to my documentshttp://www.romhacking.net/forum/index.php/topic,14708.0.html