<thead> stands for table head, so obviously it should be nested inside a table. This code is a mess (i am sorry, i wish there was a nice way to put it)
at the start of this exercise you should have:
one table, which contains
<tbody></tbody>, inside tbody you should have 3 row, each row should have 3 cells.
I recommend to reset the exercise and try again, and maybe even go back a few exercises. Maybe look through html basic 3? which explains how tables are build