I am always happy to have the a response such as saying thanks that solved the problem, but there are two other ways.
The most usual is to click the "Thanks" button on the bottom right of posts, the other is to click on the scales bottom left this applies "jelloes points" to the poster, ie the green squares you see beneath the poster's name are allocated according to the number of points, however there are restrictions on who can give such points and how often to a given helper so the thanks button is more immediate and simpler.
Hope this helps
Brian