Because there are 6 carbon molecules in 2-octene, we will place down 6 carbons. Carbons usually form a backbone, so they will be lay in a flat line. You can then add 3 H on both the Hydrogens at the ending to create symmetry, and keep filling Hydrogen on both sides and try to creat symmetry until you only have 2 H left. Place 1 H above a C and 1 H below a C so the remaining 2 carbons can then double bond to each other and form a complete octet.
