You should say what OS you have. Did you set up a backup schedule? Open Backup and check the settings and change if necessary. The first backup takes a long time and can span over days since it only backs up during idle times when the computer is awake. If you have been backing up for a while now, there might be a problem that is causing the stall. 
I noticed yesterday that the action center flag stated that a backup was in progress - it's been doing it every day for about 3 now. I don't recall triggering that action so am wondering if Dell pc doctor or some such thing is doing it. I do have a WD external hard drive for backups but it has never shown that remark before. I will go to WD site if no answers are forthcoming. Thanks. 
Backup in progress