Alex,

/tellraw @p ["",{"text":"I am "},{"text":"C","color":"blue","bold":true},{"text":"C","color":"dark_red","bold":true},{"text":". ","color":"none","bold":false},{"text":"YAY","color":"gold","bold":true}]

It will say "I am CC. YAY" with the first C being blue, the second C being dark red, and the "YAY" being gold.
plz input this into a command block (it is too long for chat)

-HexBug