You can turn on building placement grid in options, which helps place buildings so that you don't block your own production/block the wall
Terran wall is normally depots on the two edges of the ramp and a 3x3 building in the middle (rax, factory, starport, bunker, engineering bay, or armory). -x- kind of shape, X being the 3x3
http://wiki.teamliquid.net/starcraft2/Terran_Strategy has some nice stuff, if a tiny bit outdated. Also, team liquid gamers occasionally release replay packs, and liquid'taeja released one very recently and he's very good at starcrafting so you might want to look at that ^_^
Terran wall is normally depots on the two edges of the ramp and a 3x3 building in the middle (rax, factory, starport, bunker, engineering bay, or armory). -x- kind of shape, X being the 3x3
http://wiki.teamliquid.net/starcraft2/Terran_Strategy has some nice stuff, if a tiny bit outdated. Also, team liquid gamers occasionally release replay packs, and liquid'taeja released one very recently and he's very good at starcrafting so you might want to look at that ^_^