Just use the windows provided tools the almighty diskmgmt.msc .
If you have a lot of data on older partiton and DO NOT want to backup, you can expand the old partition, the other partition must be empty, formatted with same filesystem and located on right side of the old partition.
1. launch diskmgmt.msc from start>run
2. storage> disk management
3. locate which disk is your new hdd ( will be disk 1 if you have 2 drives )
4. you should see your first partition filesystem either ntfs or exfat
5. format the empty partion with SAME filesystem as existing partition, quick format is enough
6. select the old partition and chose extend volume. you should able to expand to whole hdd ( might have 8 mb left over)
And if you can backup the old...