Importing mesh to skeleton


I Downloaded a 3d model (.obj) and imported in blender for exporting to ue4. When I import it to ue4 I notice it doesnt have a skeleton so all the previous animation doesnt work and without a skaleton its also impossible to create animations.
Now the question is it possible to export the ue4 basic third person skaleton and merge it with the mesh I have (in blender or ue4)? So that I can use the same animations or is it easyer to create a skaleton and create with that the animation.
I’m a total noob at blender so a tutrial how to do it exact or a good explenation is very usefull.

Thanks in advance and sorry for my bad english