Can you keep one side of formula from changing while you drag or copy an the second part of formula

I have a worksheet in excel in row 1 & 2 the cells in column A & B are blank. In row 3 under column A start a list of names. In row 3 under column B is a list of percentages. In row 1 under column C is a number for a budget. In row 2 unders column C is a formula =sum(c1-the number that is the difference of last years and this years budgets. Now my question is how can I get the formula to run across row 1 under the following columns D,E,F ..... so that the first part of the formula stays =sumB3 and the second part of formula changes to reflect the figure under the new column.
example =sum(B3.C2), next column =sum(B3.D2), next column =sum(B3.E2) and so on with out haveing to change each one after trying to drag the formula or coping across that row.