Cocoa butter crystallizes into various types of crystals depending on the temperature at which it cools. If the butter cools into an ad hoc assortment of crystal types then they don't arrange themselves uniformly and the chocolate will be dull and sticky.
The process of melting chocolate to encourage proper crystal growth is called tempering.
You will find quite a few questions on the subject here.
You can use any chocolate that contains cocoa butter. However, if you are going to be putting that much work into tempering your chocolate you might spring for the nicer quality chocolate and not just plain Hershey's.
Alternatively, if it meets your needs, you can either serve your chocolate still melted or make a thick syrup/fudge dip that stays soft and doesn't need to be tempered.