Assuming you wanted to mount a share named 'Devel' on a Windows box named 'denali', like cifs://denali/Devel. You would first test this via Cmd-K and then
open NetInfo Manager, which lives in Application/Utilities
click the lock to be able to make changes
click on mounts
click on New in the Toolbar
click on the entry in the lower frame and start adding row, by clicking New again