Sales Projections - I'm stumped!

I'm sure I'm overthinking this one, but I just can't seem to figure it out! I am putting together a very basic spreadsheet for sales totals and it includes a column for a projection through the end of the year. Basically, we want to be able to tell the salesperson each month what their monthly and year-to-date totals are, where their goal line is, and what the projection would be through the end of the year based on their sales averages year to date. Any ideas?

Thanks!