Locking down all Cells:

There are times when working in Excel that you want to protect an entire worksheet from someone making changes to it, without protecting the entire workbook. Excel allows you to protect a particular sheet.

To simply protect the sheet your working on, right click the worksheet tab and select Protect Sheet

From here it gives you the option to password protect

You can even restrict whether you want them to select the cells that are protected

Note: Deselecting ‘Select locked Cells’ option means the user won’t be able to click into the cells within that sheet

 

Unlocking certain cells:

To give the user only access to certain cells, you first have to unlock the cells that you want the user to enter data into

So highlight these cells and right click anywhere within the highlighted area;

 

Tip: To highlight multiple areas (as above), use the CTRL Key when highlighting

In the right click menu, select the Format cells option

Under the protection tab in the Format cells dialog box, untick the Locked option

Now when you password protect this sheet, the user will only be able to enter data into the cells you have just unlocked.