Well I can make friends in RL and online.. The trick is to not expect too much of them... Especially on sites like this..
The other person may not have written back because they're having a bad day or bad week and you asked them something simple like, 'How's it going?'
And that person may still like you and may be more than willing to talk about other things with you...
Also, maybe it's good if you give yourself a pleasant nickname or at least something neutral? So that just by talking to you people can associate you with something nice or uplifting? And it's good to talk about different things, thus not overwhelming people too much with one topic or such..
If you vent about something, it may be good to discuss it with several people, not just one.. Ideally with some in RL too, cause they can bring a different perspective about it..
There are lots of tips and tricks on how to establish and maintain friendships.. and good communication.. so I really recommend learning more on this, there are books and sites..
Sometimes it's not easy to do good communication stuff if one feels sucky etc, or if you feel too good you might get hyper too lol.. So, just take your friends like people who may have troubles in RL and may be a bit busy at the time.. And if you have something of interest to them write them anyway and not expect answers.. If they answer, it's a bonus!
The thing about getting friends, is being a friend first.. It was really eye-opening for me to think about it this way.. And it's important to give people space and when they want to talk they will, otherwise you can find new and more exciting friends to hang with, meanwhile..
I do recommend learning more about communication and such meanwhile..