That tool can be a bit daunting at first sight (so much power, so many variables, such syntax), but I've just discovered a way (probably one of many...) for finding collocations (specifically).
Go to the site and click on the third radio button (labelled 'compare words'). This gives you three boxes. Here's an example of a search:
box 1: great
box 2: big
Click on the 'Search' button. After a second or two you see a split window comparing the relative strengths of the collocations "great event" and "big event". I'm not sure what 'score' means here - it probably explains somewhere on the site. But it's clear that the collocation 'big event' is nearly twice as strong as the collocation 'great event' (1.34 as against 0.81).
PS And, to get results more relevant to this specific question use these inputs: