Hi Tim,
Just to make sure, you're getting all of the Left Hemisphere files and running an ANOVA on those and then the same steps for the right hemisphere? You should then have two outputs from 3dANOVA, one being something like lh.bucket.gii and the other being rh.bucket.gii.
Once you open SUMA with the fsaverage_both.spec (or either the fsaverage_lh.spec/fsaverage_right.spec), right click on the brain and press Control+s to open the Surface controller to select your bucket file. You may have to change the default wildcards in the open dialogue (I would change it from the defaults to *), then you should be able to just open your output GIFTI (.gii) file from 3dANOVA. Select the appropriate sub-bricks as you would in AFNI and adjust the slider.
If you're still confused, maybe tell us your 3dANOVA command and the steps you're using!
Best,
Peter