Alkenes and Alkynes have similar naming rule as with Alkanes. Alkenes are hydrocarbons with one or more double bonds. There is one special property by Alkenes, some molecules have same structure but different geometry are called Geometric Isomers. There're mainly 2 types of isomers, cis and trans.
Alkynes are hydrocarbons with one or more triple bonds, their general formula is Cn H2n-2, they have similar naming rules to alkenes except they do not have geometric isomers.
Here is a link to show you what Alkenes and Alkynes really are:
http://www.youtube.com/watch?v=7XbYhjyUI-M
