Exploring a valid block involves several steps.
To get started, you need to know which block you're extracting from, which is specified by the previous block hash.
Next, you need to get a merkle root that locks a valid set of transactions. Usually, this is a set of transactions from the mempool + coinbase transaction, so that there are no double spend or invalid transactions. These transactions are assembled in a merkle tree, from which the merkle root is placed in the block header.
The coinbase transaction in particular is important, as it must follow the coinbase transaction rules (inclusion of block height, correct output for block reward, extraNonce). It should be placed as the first transaction in the block and contains the output that sends the BTC to your wallet.
Finally, you need to add in the other fields such as block version, time, nonce, etc.
This full 80-byte block header is the hashed payload compared to the target value. If your resulting hash does not meet the target requirements, you must modify the nonce in the block header, extraNonce in the coinbase transaction or one of the transactions in your merkle tree to get a new merkle root and hash the new block header. This process is repeated until you find a valid hash for the target.
In order, your approach would be like:
- Get a list of transactions you want to include (this can be an empty list)
- Select your wallet address to receive the blocking reward
- Build a coinbase transaction that pays this reward to your selected address (plus transaction fees)
- Make coinbase tx first on your list
- Build a merkle tree from this list
- Select the merkle root in this tree
- Continue as you already do