To lock only certain cells in Excel:

1. First, unlock all cells by selecting the entire sheet (Ctrl + A), right-click, choose Format Cells, go to the Protection tab, and uncheck "Locked".
2. Then, select the specific cell(s) or range you want to lock, right-click, choose Format Cells, go to the Protection tab, and check "Locked".
3. Finally, protect the worksheet by going to the Review tab and clicking Protect Sheet. Set a password if desired. Only the locked cells will be protected from editing once the sheet is protected.

This method lets you lock specific cells while leaving the rest editable.