Three lessons on algebra - so don't laugh please!

I am working on a gcse practice sheet - but I am unable to understand: y = 3x - 2

The given values are :

x -1 0 1 2 3

y ? -2 1 ? 7

Unsure if I've put this problem across clear enough, but I then have to draw this equation y = 3x - 2 on a grid.

Please help if you can.