mmikee, the 50/50 pg/vg @ 60 mg/l would be your nicotine base. You enter those three values (50,50,60) into the calculator. Then you define your 'mix' parameters; final nicotine concentration, %PG and %VG along with the quantity of the finished blend. You also enter your flavorings (name and percentage) and the eJuice Me Up calculator will tell you the quantities of nic base, PG, VG and flavorings to add for your final product.
It's pretty easy to understand once you download and install it. Give it a try and good luck! BTW, it also has some recipes in the library to give you a head start and some ideas (File>Open from the main menu).