Relational Alegebra and SQL Queries

Hey there, I fairly new to SQL stuff and I'm just trying to learn the basics and do some simple questions. I hope you guys can help me out do some practice questions.

For each of the following, (1) provide a relational algebra expression that will correctly produce the
result set required by the query. You may provide the expression as one assignment with several
operators, or as a sequence of assignments as shown below. Then, (2) create an SQL statement
that will generate the equivalent result

A) List all the teams that are located in the city "New York".
B) List the average ticket price for all the tickets in "Atlanta". You may use the SQL function AVG(price)to assist with this calculation.
C) List the names of all the players on teams named "New Jersey Devils" with salaries greater than \$1,000,000. For the SQL query, sort the list in descending alphabetical order.

Here are the tables:
http://tinypic.com/r/23r0fu1/8

I'm not too sure even how to approach this, can someone help me out?
Thanks.