Creating a wallet in Bitcoin is incredibly tricky. Depending on your need, there is various tools that will help you to reach your goal.
A Bitcoin wallet must do the following:
- Generate addresses.
- Recognize transactions spent to these addresses.
- Detect transactions, those are spending from these addresses.
- Show the history of the transactions involving this wallet.
- Handle reorgs.
- Handle conflicts.
- Dynamically calculate transaction fees.
- Build and sign transactions.
- Broadcast transactions.
Doing all of this by yourself from scratch requires serious skills and experience. Luckily there are tools you can utilize.