Ghost Shifting and the solution.

Hey all.

I have been experiencing some ghost shifting while cycling in the 2 highest gears. I visited the bike shop today and asked about the problem and was told I should index the shifting (not sure the wording here). I recently replaced the chain and the derailleur looks fine.

Will indexing help me solve this problems ?

P.S. As I am doing longer riders away from home I am trying to learn to fix the most frequent problems that come alone during a 50 km+ rides.