Your MSPs represents you in the Scottish Parliament. The Scottish Parliament is responsible for a wide range of devolved matters in which it sets policy independently of the London Parliament. Devolved matters include education, health, agriculture, justice and prisons. It also has some tax-raising powers.
Your MP represents you in the House of Commons. The House of Commons is responsible for making laws in the UK and for overall scrutiny of all aspects of government.
You can write to any representative, or your local councillors through WriteToThem.com.