computer help, merge unallocated partitions into one

I'm having a lot of issues trying to merge my unallocated space or just combining the space all onto c drive, I spent hours last night downloading software and messing about trying to figure it out but I couldn't, I really need this space combined to download a 157gb file or ill need to buy an external drive. attached is a screenshot from the partition manager, if you know about this sort of thing please apply, need someone who knows what they're doing