To fix the board-to-board connector, you can follow the following steps:

1. Prepare tools and materials: Make sure you have the required board-to-board connectors, screws and nuts, and a suitable screwdriver or wrench.

2. Align the connectors: align the two boards to be connected, and ensure that the connectors are positioned correctly and the slots or holes correspond to the boards.

3. Installation of screws: Fix the connector on the first board with screws. Make sure that the screws pass completely through the connector and leave enough length to connect the second board.

4. Connect the second board: Place the second board on the connector so that the screws pass through the holes or slots of the board.

5. Fixing nut: On the other side of the second board, use nuts to fix the screws. Make sure that the screws and nuts are tightened, but not too tightly to avoid damaging the board or connector.

6. Check the connection: Finally, check whether the connector is firm, whether the plates are aligned, and whether the screws and nuts are firm.