Welcome to the forum!
I'm not familiar with tapatalk, but here are the instructions that work for me.
http://www.tnttt.com/viewtopic.php?p=911290#p911290If you link the image URL into your post the pic will come in at the size that you reduced it to in your gallery.
If you link the BBCode it will come in as a click-able icon.
I personally like the bigger pics, myself, and people don't have to jump around so much when trying to read thru while checking details.
Regarding the aluminum skins, most people seal the perimeter and around penetrations (doors/windows/roof vent) between ply and skin with sealant/caulk/goop and staples, allowing the field to float; and then they use RV trim molding (bedded in more sealant) screwed to the wall to roof corners. The vinyl molding snaps into the track in the trim to cover the screw heads.
Alaska Teardrop's, for one, has used an adhesive backed corner trim that goes over the screws (or rivet heads, in his case) all in one shot.
http://www.tnttt.com/viewtopic.php?f=27&t=51991&p=956704#p956704Some people use contact adhesive to attach the aluminum over the whole field, but the consensus is that heat from the sun will quickly expand the aluminum and break this bound, so they are relying on the perimeter method in the end anyway.
Check out some builds in the traditional "Build Journals" section of the forum. Aggie79/Tom's
Silver Beatle is also a great resource for how to do aluminum skin, IMO.