So I have SimPE but I've rarely used it. I think what I'm trying to do is so simple that there are no tutorials on it lol (or at least none that I can find).
I want to use Midge the Tree's spell mod and she said if you don't use her fairy life state (which I don't), you need to change the BCON on Magical Fairies from 1 to 0. I have no idea how to do that.
I've opened the mod in SimPE and in the Resource Tree I see "Behavior Constant (BCON) (31)" but when I click it nothing happens and therefore I cannot find anything to edit. My apologies for such a simple question.

1 - Select the line in Resource Tree Bahavior Constant (BCON) - This filters the resources in the Resource List to just the BCON resource
2 - Select one of the BCONs in the Resource List paying attention to the BCONs Midge says you don't edit
3 - Select the second line in Plugin View (0x01)
4 - Change decimal value from 1 to 0 - Changes from True to False
5 - Commit/Save

The image doesn't show it, but off to the right in Plugin View is where the Commit button is. The plugin view on the bottom is pretty much where you edit any of the resources. You select the resource in the Resource List, then edit in Plugin View. You may be interested in checking out this tutorial which explains a bit about SimPE.

Thank you so much! That was so simple. My issue was that the Resource List was never appearing when I opened SimPE, that's why I had no clue what to do. But I fixed that, followed your steps, and voila ~ no magical fairies