Stuck on a SUMIF function

Hello!

I am racking my head trying to figure out this formula. I'm trying to do a home expense report and can't figure out how I can get a total of how much I spent on a certain category. For example, I want to sum up the amount I spent in Auto & Transport in a seperate column so I can index it each month.

Column A Column B
1 $23 Auto & Transport
2 $10 Groceries
3 $12 Groceries
4 $14 Auto & Transport

I have a seperate column C with Total of Auto & Transport and I want the formula to say something like:

If Column B1:B4 = "Auto & Transport", then sum "Column A1:A4". The amount would be in a seperate column ie: column D1 and it would equal $37 ($23+14).

Please help!

Grrrrrrrrrrrreat! Thank you! so easy!