I NEED STEEM IT HELPPPP

hey guys, so far im enjoying steem it but theres alot of things im finding difficult to understand, ive seen a few posts but some are from 2 years ago and are outdated
Firstly i really wanted to promote my content because i want more people to see it but my major problem is i cant by steem dollars with actual money

If anyone knows how i can invest in steem and buy steem dollars, it will be highly appreciated.