Start by registering for a Coin API account if you haven't already. After registration, obtain your API key, which is necessary for authentication. Familiarize yourself with the Coin API documentation to understand the available endpoints and the data format (usually JSON).

Use a programming language like Python to send HTTP GET requests to the Coin API endpoints. You can utilize the `requests` library to make these requests. Here"s a basic example in Python:
```python
import requests

api_key = 'YOUR_API_KEY'
url = 'https://rest.coinapi.io/v1/exchangerate/BTC/USD'
headers = {'X-CoinAPI-Key': api_key}

response = requests.get(url, headers=headers)
data = response.json()
```

Once you've fetched the data, parse the JSON response to extract the required information. Depending on your needs, you might want to restructure the data into a format suitable for loading into DuckDB, such as a list of dictionaries where each dictionary represents a row.

If DuckDB is not already installed, you need to install it. DuckDB can be installed via pip for Python by running:
```bash
pip install duckdb
```

Initialize a new DuckDB database or connect to an existing one. Define a table schema that matches the structure of your parsed data. For example:
```python
import duckdb

conn = duckdb.connect('coin_data.db')
conn.execute('''
CREATE TABLE IF NOT EXISTS exchange_rates (
time TIMESTAMP,
asset_id_base VARCHAR,
asset_id_quote VARCHAR,
rate DOUBLE
)
''')
```

Convert your structured data into a format that can be easily inserted into DuckDB. Using the connection established, insert the data into the DuckDB table. Here"s an example assuming you've structured your data as a list of tuples:
```python
data_to_insert = [
(response['time'], response['asset_id_base'], response['asset_id_quote'], response['rate'])
]

conn.executemany('''
INSERT INTO exchange_rates (time, asset_id_base, asset_id_quote, rate)
VALUES (?, ?, ?, ?)
''', data_to_insert)
```

After inserting the data, it's crucial to verify that the data has been correctly loaded into DuckDB. Run a simple query to fetch and print some rows from your table:
```python
results = conn.execute('SELECT * FROM exchange_rates LIMIT 5').fetchall()
for row in results:
print(row)
```

By following these steps, you can effectively move data from Coin API to DuckDB without relying on third-party connectors or integrations. Adjust the steps based on your specific data requirements and use cases.