after you have created a spine object in C2, right click the "files" folder in the right hand side project folder list and import the .atlas, .json and .png image that you exported from spine.
then on thet hand side properties window, you fill in the 5 empty fields.
Spine Data URL: character.json
Atlas Data URL: character.atlas
Skin Key: default (or whatever skin name you are using)
Anim Key: walk (or whatever your animations names are)