for hybridization u have to check the no of sigma bonds.

 for example in methane the no of sigma bond is 4

 

so the hybridization w'll be sp³    (s,p,p,p,d,d,d)

 

now in case of ethene

the no of sigma bonds formed by c is 3 so the hybridization w'll be sp² (s,p,p,p,d,d,d)