First, log into the administrative mode of your pool. Then, in the General Rules, check the check box "Use the "Count top X" feature". Now go into the Scoring rules section. At the bottom of this page, you have the section to configure the "Count top X" feature. Use either the count top X per type or the count top X for the entire pool (regardless of the pick type) or you can use both.

For example, suppose that each competitor in your pool has 10 forwards, 5 defencemen, 3 goalies and 2 teams.  If you want to count the 15 highest picks regardless of the pick type, you'll write 15 in the "Count a total of X picks" field.  If you want to count at least 2 defencemen, exactly 1 goalie and 1 team, and 6 other players (within the forwards or the defencemen), for a total of 10 picks. For the defencemen, you'd write 2 in the "Keep at least X picks (minimum) : " row. For the goalies and the team, you'd write 1 in both rows (to keep exactly 1 team and 1 goalie). Then, you'd write 10 in the "Count a total of X picks" field (regardless of the type).