At this point maybe you should
1- read what was said (the user needs to double-click on the locked
cell he wants to edit)

2- try to make it (because you need your "first time")



Just lock the cells you want to protect, protect the sheet, and type in
the macro in the VBA editor (the code must be associated with the right
sheet)


If you realy don't know how the VBA editor works, maybe you should
read and try with examples (take a look on the web for tutorials) or ask
a friend... But at this point you should stop asking and start trying...

this "learning time" is required.