Everyone has to start somewhere. I started on Upwork, not the most glamorous place to begin but I am indebted to it nonetheless. This was the first time I was ever paid for a bit of my writing and even though a lot of it was ghost writing, it was very rewarding.
I call these beginning freelance websites because they are a good place to build up your portfolio but most people do not make an extensive amount of money on these. For sites like UpWork, there will ALWAYS be people who underbid. There will always be clients who thing that $2/hour is reasonable for website management.
So until you're ready to take what you've learned (and the money you've made) and start finding clients outside of these sites, check which one will work for you.
Competition is HIGH and it is incredibly difficult to land a job without prior experience on Upwork. Each month, you receive 60 "connects" and typically it takes two to submit a proposal. You also get rollover connects if you don't use all of them.
Competition is slightly lower but you also receive far less bids than you do on Upwork. The free account starts you at 10 free bids per month. That really isn't much and it stressed me out at first, but there is a lot less competition so your bids are more likely to be seen.
The selection process to be a freelancer is a bit more difficult. You have to apply and complete your profile and then you can begin. You can post "hourlies" which are services that you will give for a predetermined rate or charge. I like the concept but I had a hard time getting anyone to pick my hourlies. Looking at the statistics I think I might go back and refresh some of my stuff on there.
This is a marketplace where tasks and services are given by freelancers and posted under (generally) a $5 price mark. You can increase this, add extras, faster shipping, etc but the idea is a low cost one time project.
Statistics (hard time finding concrete numbers):
This marketplace is similar in a lot of ways to Upwork. It is different in that you only get 8 free bids a month (yikes) but the dashboard is nicely organized and easy to read.