Can I calculate cell from formulas in drop down list?

[WhatBackHand]

I don't know Excel so I'm after some advice. I'm trying to write a spreadsheet that records my working hours, mileages etc. I work on several projects that have different rates for normal hours, overtime and weekend working, etc. For each day I'd like to calculate "my wages" based on, probably a drop down list picking the rate for that day/job and display the result accordingly. These daily calculation then get summarised on monthly and annual sheets. I can cut and paste the correct formula from previous days/calculations but this is getting tedious, I'd like to make the spreadsheet to do at least some of the work!

I have no idea where to start, I can find nothing that points me in the right direction in the Excel helpfiles and only have access to a basic Excel book. I'm making the assumption that this would be possible?

It's also likely that I'm using the wrong terms which is why my search in Excel is coming up blank.

So, some pointers to some online resources or books or even just to the right terms to throw at Excel would help.