Help me finish off my site? PLEASE!

I posted earlier and got some great help, but am lost with the rest. I’m trying to finalize my site, see my bullet points below . . .

? Sidebar aligns to top on firefox, but not in safari.
? Validating it shows I have a TON of errors/warnings, but it’s way too over my head for me to sort through.
? I need the sidebar to reach to the bottom of content.

Anyone willing to help me out on these? I need SIMPLE, SIMPLE, SIMPLE explanations since I’m fairly new at this. Please help me finalize this blog quickly?!

https://www.uniqloveblog.com