You need another forum member to give Merit to one of your posts.
For each Merit you get, you also get 0.5 sMerit, which is Merit that you can give to other people.
So for example if someone gives you 4 Merit, you also get 2 sMerit to hand out. When you give the 2 sMerit to someone, they gain 2 Merit and also get 1 sMerit to share.

All members above a certain rank got a small amount of sMerit to share to start with when the system was introduced, but new sMerit only comes into the system through a few people who are 'merit sources' - these people have been chosen because they are well-respected on the forum and have good post history. These merit sources are the only people who receive new sMerit to share out. All other sMerit is just recycled through the system as outlined above.

The merit system is good, but one problem is that because people only have a very small stash of sMerit with no guarantee of receving more, people have been very reluctant to hand it out.