I have coded my game using only .chr file , as .chr is not enough I made other but what are the changes that I should make in my code to include and use the other .chr , I am just a starter for switching the data, so please try to explain clearly.
You need 2 file types. A .ASM file, and inside that you "include" the .BIN file (Characters). In the iNES header, you type in how many program banks you have and how many character banks. You adjust those numbers at the top in the iNES header statement. The PRG is in multiples of 16 and CHR in multiples of 8. So if ines header character value=1, You have 8KB of character ROM. If it is 2, you have 16K. But remember, if you have more then the NES can handle you need to add a mapper to swap those baks around as needed.
The first banks are the program....IIRC.....Then after that all those banks are characters....
OK, you reached one of the limits of the NES and it's now time to make a decision: which mapper to use?
To go beyond the memory limitations of the NES (32KB of PRG, 8KB of CHR), you have to use a memory mapper. Which one depends on what you plan on doing from now on.
The simplest mapper you can use to solve your problem right now is mapper 3 (CNROM). With this mapper you can have up to 4 CHR-ROM pages of 8KB each, for a total of 32KB of CHR. The disadvantages of that mapper are the fact that it has no bankswitching for the PRG (so you can't have more than 32KB or PRG) and that it can only swap the whole 8KB of CHR at once (so depending on the type of game you are gonna have to repeat tiles across the different tilesets, like the tiles of the main character, which must be available at all times).
If you are OK with those limitations (you know that the PRG will not take more than 32KB, that 4 pages of CHR are enough and that tile repetition is not a problem), CNROM is the way to go. Like 65024U said you have to change the header to indicate how many pages of CHR are there and the new mapper number, as well as .incbin the new pages after the one you already have (like I told you by PM).
However, if CNROM is not enough for your needs, you have to choose another mapper. Personally I suggest mapper 2, UNROM. The big difference is that it uses CHR-RAM, as opposed to CHR-ROM, which means that the CHR data will not be automatically mapped to the PPU, you'll have to copy it to the PPU yourself in the program code. I'll not confuse you with that for now though, since CNROM might in fact be enough for your needs.