How can I get my boyfriend to post about us online?
Why do you want your boyfriend to post about the both of you online?
I want everyone to know how much he likes me.
I don't think it's reasonable to expect your boyfriend to post about you on the internet. It's not right to try to get him to say things publicly that he wants to keep private. I think you should respect his boundaries.
So what, he's a coward. Who cares?
You should wait for your boyfriend to feel comfortable in posting about you online. If you push it, you may create unnecessary conflict.