Pinyin: the "ch" "sh" and "zh" sounds

The sounds represented by "ch," "sh," and "zh" in pinyin are all very similar sounds in Chinese. They're meant to be grouped together, and they should be learned together. The good news is that these sounds are not too different from the English "ch," "sh," and "j" sounds (note that "zh" sounds like the English "j" sound; the pinyin "j" sound is totally different beast, to be introduced later).