Niiiice! Thanx for the shoutout man and jeez these tutorials are awesome!!
I use Gimp too (shoutout to the FOSS Devs over at gimp.org!), it smokes photoshop imo.
Also, you mentioned Tinypng.com which I love. Usually in Gimp I will resize my final image there to the desired pixel dimensions, then export the image to both png and jpg with a tiny bit of compression and as little metadata and other crap as possible, then upload both of the images to tinypng.com and usually see anywhere from 40% to 80% shrinkage on the filesize. Grab the smallest one for upload to your page. For people on mobile especially, this is hugely important so that your pages will load wicked fast and not burn up their bandwidth unnecessarily.
I will do my best to help spread the word about your channel Unkle Bonehead, luvin it!! :)
RE: Making My New Cover Image