Protecting spreadsheet elements
Protecting spreadsheet elements is a two-step process. By default all cells are locked. You must first select and unlock the cells. Then, you must turn on protection on the entire spreadsheet for the "lock" to go into effect.
1. To unlock cells on a spreadsheet, see Locking Cells in a spreadsheet.
2. To hide any formulas that you don't want to be visible, following:
2.1. Select the cells with the formulas.
2.2. Click Format -> Cells, in the Protection tab select the Hidden check box.
3. To unlock any graphic objects (such as pictures, clip art, shapes, or Smart Art graphics) that you want users to be able to change, do the following:
3.1. Hold down Ctrl and click each graphic object that you want to unlock.
3.2. On the Format menu, click the command for the object you selected: AutoShape, Object, Text Box, Picture, Control, or WordArt:

3.2. In the Protection tab clear the Locked check box, and if present, clear the Lock text check box:

4. Now you must protect the entire spreadsheet to have the lock feature protect the cells that you selected. Select the Tools -> Protection -> Protect Sheet....

4.1. Enter a password if you want to require a password for "unprotecting" the spreadsheet.

4.2. In the Allow all users of this worksheet to list, select the elements that you want users to be able to change (see Protect Excel spreadsheet options).
4.3. Click OK.