Website displaying incorrect on some OS or Browsers – Browser Detection Plugin?

hi there, my website is up and running after much effort (i am not very web savvy at all) and when I have asked some people to check it and see what they thought, some people said it didn’t work or it wasn’t displaying properly.

In particular windows operating systems and internet explorer older versions. Personally I have only checked it on mac and it works fine, but my partner and sister checked on their work computers which were pc and my partners displayed the slideshow on the home page but no menu, and my sister also on a pc saw the menu but no slide show and the bar running along the bottom was through the middle of the page.

i have looked at plug ins for browser detect and quiet frankly it made no sense what i was to do with this.

If someone can explain to me in simple terms (or as simple as can be to a bit of a web illiterate person) or has any easy solution that would be amazing!

Thanks so much!

Tim
takenbytim.com.au