the line weight needs to be the same as your rod spec... 6wt rod = 6wt line (general rule, you can use heavier line to load a rod faster etc)
dry fly normally requires a /floating line
onto the flyline, you tie a leader
onto the leader, you tie some tippet
for typical NZ conditions I would look at 3X leader, and 4x to 6x tippet
learn to tie a perfection loop, loop-to-loop connections are great for connecting all the pieces together
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