How to change the color of a single bar if condition is True

You need to use color instead of facecolor. You can also specify color as a list instead of a scalar value. So for your example, you could have color=['r','b','b','b','b']

For example,

import numpy as np
import matplotlib.pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(111)

N = 5
ind = np.arange(N)
width = 0.5
vals = [1,2,3,4,5]
colors = ['r','b','b','b','b']
ax.barh(ind, vals, width, color=colors)

plt.show()

is a full example showing you what you want.

To answer your comment:

colors = []
for value in dictionary.keys(): # keys are the names of the boys
    if winner == value:
        colors.append('r')
    else:
        colors.append('b')

bar(ind,num,width,color=colors)