One common way is to use a reputable wallet software or app, like Bitcoin Core, which is the original Bitcoin wallet. and here is its official website: https://bitcoin.org/en/bitcoin-core/

The scriptSig contains the signature created by the private key of the sender to prove ownership of the funds being spent. It also includes the public key or address of the sender. This signature is used to verify that the sender is authorized to spend the funds. While the scriptWitness contains additional data required for certain types of transactions, such as Segregated Witness (SegWit) transactions. SegWit is a technology that separates the signature (witness data) from the transaction data, which helps reduce transaction malleability and increase block capacity.