Adjectives change according to the gender and the number of the noun which they qualify.
When an adjective refers to a group of masculine and feminine nouns, only the masculine concordance rule applies. Some adjectives are placed before the noun they qualify rather than after. Il conduit un camion et une voiture bleus 2. Note that the concordance rules apply to the adjective according to the gender and the number of the subject. I advise you to buid such sentences using the few words you have already learnt.