Sorting out the files
The output of randomise are statistic, p value, and corrected p value files, for each contrast. The contrasts to which statistics files correspond are indicated by numbers, e.g., *_tstat1 (or _fstat1), *_tstat2, *_tstat3, and so on. For a two-group design matrix, you will typically have four contrasts; these are listed in the *.con text file created when you create the design matrix with the Glm GUI. Below is an example:
Quick look
Open a p-value file in mricron, and look at the histogram (Ctrl^H); this will quickly show you whether there are significant p values. Remember that FSL saves these as 1-p value, so p = 0.05 will be recorded as 0.95 in the file.
For multiple t or F contrasts, you will need to know what "tstat1, tsta2, tstat3,...etc means; you can open the text design files to verify.
Opening the mask file in a separate, yoked mricron will allow you to ensure you have the cursor on a surface voxel.