I think karma will come to your account depend on post qualities, if you have good and educative post seems not difficult your karma will increasing depend on how many meaningful or your post. the same with other forum on bitcointalk, appreciated by sending merit if you have educative or meaningful post.
First need increasing post qualities and then you will get large amount increasing karma with your account, admin have rule with karma system and need to make better post in the future in want get many karma points but the sender or karma get limitation in daily day around each 10 hours for sending it.
Since the OP wants to know about karma and how to give karma or when to give karma, they should discuss these things. To whom he will give karma or to whom he will not give karma is entirely his own matter. If the post is constructive and another member benefits from reading that post then that member can give karma to another member. However, a member cannot give karma at will because the minimum qualification for him is to be a senior member. That is, starting from every senior member and above all members can give karma to other members.