That is just an overflow hose, you just let it hang down below carb. That looks like the carb I am running on my 48cc. The jets are inside. I am running a 85 main and a 25 pilot jet, a 2.0 slide (that number is stamped on the underside of the silide) and the jet needle set on the second from the top slot. I also have ported the intake and exhaust ports to match manifolds, and am running a pocketbike expansion chamber. I am in Florida at sea level. I would think this would be a good starting point depending on where you live, just keep and eye on you plug as you start adjusting the mix...
Here is an exploded view that will help you with assembly and disassemly...