How to use a drop down list to input data from another sheet?

At my job we have two spreadsheets and i am trying to combine them. The first spreadsheet is used to input their credit card tips and then spits out their total tips after tip outs/ins. The second essentially give daily totals per person. Right now we manually transfer totals between the 2 and I'm trying to automate this using a drop down list to move the data into an end of week spreadsheet that has everyone's totals but i know very little about excel and im not sure how to acheive this. Any tips?