Writing an IF THEN function

[tgivens08]

I'll start this ask off by first stating, "I AM NOT A DEVELOPER". If at all possible, please give me the cliff notes, developer for dummies version of an answer. 

Problem: Trying to write an accumulation formula that sums actual cost by month, if the months are in the past then sum and accumulate actuals, and if the months are >= today then sum and accumulate the forecast. Example: Accumulate Jul-Jan = Actuals + Feb-Jun = Forecast. This will appear in a combination chart where the monthly actual/forecast will ultimately show an Estimate-At-Completion. 

I have all elements of this chart except the accumulation line.

I've created all of the elements of this chart but cannot create a function to achieve the "accumulation line". 

Please help. 

[chris_djih · Accepted solution]

You can use an if Statement, which is build as follows:
=IF( condition, then, else )

So in your case:
=IF( YourMonthField <= Month(Today()), Sum(Actuals), Sum(Forecast) )
The last hard step is to replace the field names printed here in bold with the correct field names from your data.

[tgivens08]

Once we finally figured out the correct fields to add and applied the Accumulate Values function, this formula worked like a charm! We've worked on this for months, given up and come back again. Thank you for saving the day Chris!