Aaand one more question on Interfacing (for a hat brim)

I got some Timex Interfacing from knitpicks, came in the mail a few nights ago and I finished up a hat (pattern found in Son of Stitch 'N Bitch) called the Half-Pipe Cap.

I followed the pattern for the brim, cut it out, folded up the ribbed bottom and tucked the material in there and stretched the ribbing over it and sewed it closed and whatnot. Well, this interfacing stuff seems kinda flimsy… And the package didn’t really come with any directions. Was I supposed to steam press it or something? Before or after I attach it to the brim? Also, it was all folded up so at the fold marks it’s especially flimsy and floppy, and now the brim of my cap has a little dink in it.

Should I make it double or even triple thick? Is there a trick to “setting” the shape of the interfacing? Or did I just get the wrong kind of material for a firmer cap brim?

I’m not sure so I’m bumping this for you.