Each salesperson can be given a sales target for every month of the year.
Open Sales Management → Sales Partner Management, select the rep in the list
and click Details, then click the + button beside the Target field
(you do not need to click Edit first). See also Sales people setup. A window lists the twelve
months; type the target amount for any month and click Save. Leave a month
blank if it has no target.

• The + button is visible only to administrators and sales/marketing leaders,
  and is enabled only after the sales rep has been saved (a brand-new, unsaved rep
  has no record to attach targets to yet).
• Only the target value is stored from this screen. Any actuals or variance
  figures produced by sales reporting are left untouched.
• Targets are by month number (January–December) and are reused each year;
  there is no separate per-year target.
• This is separate from the Target drop-down itself, which links the rep to a
  pricing target matrix — a different setting.