Every actions on the blockchain uses resources with some using more than others
example a comment or post will use more than an upvote

you get more resources by powering up hive, the system is there some 0hp accounts cant spam the system to death.

You can check your resources
http://hiveblocks.com/@drbenzz

another useful site is

http://hivestats.io
this one gives you all kinds of info

i will delegate you 20 hive till the end of this month so it gives you time to earn and power up some hive which will help with your resource credits