Adding win percentage to a Pandas DataFrame involves calculating the win percentage for each row and then adding a new column to the DataFrame to store the results. Here's an example:

import pandas as pd
 
# Create example DataFrame
df = pd.DataFrame({'Team': ['A', 'B', 'C'], 'Wins': [20, 15, 10], 'Games Played': [30, 30, 30]})
 
# Calculate win percentage for each row
df['Win Percentage'] = df['Wins'] / df['Games Played']
 
# Print the results
print(df)

Output:

  Team  Wins  Games Played  Win Percentage
0    A    20            30        0.666667
1    B    15            30        0.500000
2    C    10            30        0.333333

In this example, we create an example DataFrame with columns for Team, Wins, and Games Played. We then calculate the win percentage for each row by dividing the Wins column by the Games Played column, and assign the results to a new column called Win Percentage. Finally, we print the results to the console.

Note that the column order is preserved in the new DataFrame, so the Win Percentage column is added as the last column. If you want to reorder the columns, you can use the reindex() method or simply select the columns in the order you want them.