Please help me with these questions,

a)Rent Seekers in the domestic Shirt industry have requested that the government place a $2.00 per item Tariff on imported Shirts. Describe and explain the winners and losers from this action. Please also help me with a diagram.

b)In general why would Governments place Tariffs on any items? What could be the impact of such Tariff actions by Governments?

c)How might a Tariff on a large volume high value imported item affect the supply and demand for Australian dollars? Please also help me with a diagram.