Need to learn just how to transition songs in a mix

I am completely new to mixing - all I want to do for now is to take a number of hip hop and house songs that I have for a party on saturday and string them together so that they transition smoothly.

Is there an auto feature for this? Also, I cannot find the manual for learning how to use Ultramixer. I also downloaded Audacity. Does it make sense to use Audacity instead, for a simple task like this?