Hi,
I can clean up some storage and update or also just perform clean installation after you backup your data (former one will wipe everything, so backup is important). other than that it's fairly old Macbook Air, there are a few configurations available for A1369 (Core 2 Duo, and Core i5/i7) i'm not sure which one you have. i don't think any of the Macbook Air have an Hard Drive, all use Solid State Drives (SSD) as standard Hard disk won't fit in that form-factor.
How you suggest this work to be done?
i'll prefer backup your data and perform clean installation, then afterwards we can install the apps that you need.
Please contact me in chat to discuss more.
Regards,
Hamza