I'm realy surprised there's somebody in epvp who realy want to learn how to do it.
So, there's no specified 'best' language for this. But there some 'Frameworks' which can search partical Images in one other.
I think

looks intresting for you. But it's a bit harder and remains to better knowledge (for this you need knowledge in C++). But I think it's understandable and if you want you will do it.
If don't so, i'm there to answer your questions, or just help a bit.
have fun and good luck
€:
I just want to discribe the basic function, how you can realise it.
First you have the pic which you wanna search. We name it 'needle'.
Second we have the picture in which you want to search for the needle. We call it 'heystack'.
So, to find out if the first pic is matching in the second, we need to search for pixels.
We read the first pixel (at position 0,0) from needle. Then we try to find this pixel in the heystack. If there's a Match, we read the second pixel of needle (o,1) and look up, if the next pixel of heystack matches with the second of needle. If that's true, we go on until the end of the picture. Then we explicity know, the needle pic is in the heystack pic.
I hope you understood this and it will help you.