View Grades in Forum
Depending on the instructor and how they grade their forums, there could be an extra way to see the grade in the forum. If not then you will see it in your gradebook only if it is worth any points.
View from the Forum
Click on the forum that you would like to see your grade for and click on your posting.
View from the Gradebook
To view your forum grades through the gradebook click on the "Course administration" and then "Grades"