No, atheists do not pray. Prayer is a practice of communicating with and worshipping a god. Since atheists do not believe that any gods exist, they do not see any point in praying.
The practice of prayer varies from one religion to another. In Christianity, it is often seen as being in direct communication with god. Since atheists do not believe that that god exists, there would be no point praying to him – atheists do not believe that there is anyone ‘on the other end of the line’.
In some religions, prayer is also about praising god in a ritualistic manner. Atheists see no point in praising something that they don’t think exists, so do not consider it a worthwhile activity.