Needing to get win 10 OFF and win 7 back on...

I asked someone to remove the win 10, a win 7 ultimate, but to leave the win 7 that were all installed. Not sure how to explain, but it had all 3, on a 160 gb HDD thus taking up valuable needed space. Also asked for the C (110gb) & D (40 gb)drives to be somehow COMBINED into just one usable 160 gb drive. Instead, MY new (used) laptop came back with win 10, meaning I'd have to learn to use a computer AGAIN(and told id ENJOY it) etc... and both C (120gb & D (35gb)drives, as well as the previous owner/ users files, info, etc... I TRIED the win 10, finding it difficult to navigate, very different from the win 7 I learned on. All I'd like, is for Windows 7 Hm Prem with MY libraries, and not have the previous admin, or owners name be where MY name should now be. If I'm LUCKY enuf to eventually get the 360 gb to work on this toshiba, that'd be my silver lining.
But hoping only for the simpler (for me anyway) windows 7 Hm Prem I originally wanted (and what is listed on all tags, sticker etc...
Not trying to seem snotty, or.... I'm old. Got a small plate! And it overfloweth with other bumps & bruises.
So... how can I get the original win 7 Hm Prem reinstalled, maybe combine the 2 drives into one (160), or get the other one (360) to work? Yup. More storage would be awesome, but I can't effectively use win 10 like I can win 7. PLEASE HELP?!
Win 7, MY name as user/owner, THEN maybe we can get to the storage issue?!?!?!