How do i dye the top of my hair but not the rest?

ok so I am dyingg the top of my hair light blonde at home I was just wondering
how do I only die the top and not the rest of the hair can anyone help? do I need to clip it back or something

Yeahh Babbe, Justt Clipp Orr Putt A Bobble Arouund The Bottomm Biit, Thenn Be Careful Puttiing Thhe Dyye On Top ALSO Makke Surre Thatt The Linne Between Thhe Bottom Annd Top Bit Is Straiight Or Elsee It Wiil Look Gay!
Hoppe This Helppz!
XxXxX

what I do sometimes is just get tin foil and put it on the part where you dont want hair dye to get there, I die my hair a lot.. so I hope this helps (: