Once you have created the forums from Admin panel, forums are not displayed in the front by default.
After creating forum you need to set proper permissions for the forums to be displayed. First you need to set Global Permissions.
ACP->Forums->Group Forum Permissions (Last menu link in the left column)
Once you have selected that you will see Look up usergroup: drop down menu, select the Registered Users from the drop down menu and click submit.
From next page select the Forum and click Submit
From the next page you need to assign the desired permissions.
Select the Forum Permissions from the Permission Type
Then select the desired permissions.
If you are not too sure what they mean then select Standard