It’s called your Dashboard. Look for the word “Spam” in the section called “Right Now”. The word itself is the link, the number beside it is how many you have. Click on the word “Spam” and the spam filter will open.
If you can’t see the “Right Now” section, there’s a link on the upper right hand corner called “Screen Options”. Click on that and a drop down menu will appear. Click the box next to “Right Now” and it’ll appear.