Someone help i want to make my first romhack ever but I do not know how to do it 😔.
Well, there are many many tutorials on this site that can help you with this. An important decision you'll need to make is deciding whether to make your ROM hack via binary hacking or a decompilation/disassembly project.
Binary Hacking: This is a process where you have a .gba or .gbc file, and then edit the hex values of these files to make the changes that you want. This is easy to get into, but you can fairly quickly start running into ideas that are very difficult to implement with this process. There are a ton of tools that you'll need to work with this style of hacking.
This part of the forum has all sorts of tutorials and tools to help you with binary hacking, and
this part is full of people coming up with new ideas for binary hacks.
Decomp/Disassembly: This is a process where you have the source code/assembly code of the game that you are hacking, and then you make changes to the code to apply the changes you want to see in the game. This style is harder to get into, as you need to learn how to compile the code into a playable ROM, as well as possibly using Github so as to back up your code and use other people's projects as a base, but the limits of what you can do with this method are effectively endless.
This part of the forum has plenty of tutorials on how to work with this method of ROM hacking,
especially this tutorial on how to start with the most common base projects that already implement Pokemon from later generations, updated battle mechanics, and more. There's also
this area of the forum that is designed for people to ask questions relating to this style of ROM hacking.