Select all the cells you don't want to be locked. These will be the specific cells that can be edited even after the sheet is protected.
Right-click on your selection, select Format Cells, and click on the Protection tab. (Alternatively, under the Home tab, click on the expansion icon next to Alignment, and in the Format Cells window go to the Protection tab.)
Uncheck "Locked" (which is checked by default) and click OK.
Go to Review -> Protect Sheet and press OK to protect the sheet. Any cells you didn't unlock under the Format Cells option (step 3 above) will be locked, while the unlocked cells will be editable.