Ensure that your environment is set up with the necessary tools. You need to have Apache Iceberg installed and configured on your system. You will also need Python installed to handle the Excel data, along with the `pandas` and `pyarrow` libraries for data manipulation and conversion.

Use Python's `pandas` library to read data from the Excel file. This can be done using the `pandas.read_excel()` function, which allows you to load data from Excel into a Pandas DataFrame. Make sure to specify the correct file path and sheet name if needed.

```python
import pandas as pd
excel_data = pd.read_excel('your_file.xlsx', sheet_name='Sheet1')
```

Convert the DataFrame to a Parquet file using the `to_parquet()` method from `pandas`. Parquet is a columnar storage file format that is efficient for use with data processing frameworks like Apache Iceberg.

```python
excel_data.to_parquet('data.parquet')
```

Inside Apache Iceberg, create a new table schema that matches the structure of your Excel data. This can typically be done using SQL or a command-line interface provided by Iceberg. Define the column names and data types that correspond to your dataset.

```sql
CREATE TABLE iceberg_db.your_table (
column1 STRING,
column2 INT,
...
)
```

Once the Parquet file is prepared, use the Iceberg SQL command or a compatible engine like Apache Spark to load the Parquet file into the Iceberg table. Use a command such as `INSERT INTO` to move the data into Iceberg.

```sql
INSERT INTO iceberg_db.your_table
SELECT FROM parquet.`path/to/data.parquet`
```

After loading, verify that the data has been correctly inserted into the Iceberg table. You can run a simple `SELECT` query to ensure the data matches what you expect from the original Excel file.

```sql
SELECT FROM iceberg_db.your_table LIMIT 10;
```

Finally, clean up any temporary files such as the Parquet file if no longer needed. Consider optimizing the Iceberg table by running maintenance operations like compaction to ensure efficient data access and storage.

```sql
CALL iceberg_db.system.compact('your_table');
```

By following these steps, you can effectively transfer data from an Excel file into Apache Iceberg without relying on third-party connectors or integrations.