You have to wait for your resource credit to recharge. I'm not too conversant with the details but every account has a limited amount of resource credit depending on your STEEM POWER or reputation(I guess). Wait for some time for it to recharge. Whilst you're waiting for it to recharge, prepare your next blog post. Cheers
Ps: the resource credit limits the amount of activity each member can undergo or carry out in the platform. Once you exhaust your RC, you won't be able to carry out any activity.
Consider this, the RC is analogous to energy. So RC is the ability to comment and make blog post.
Cheers again. Hope this helps