There are many people who want to practise certain league/tournament games but are unsure of the correct settings. It really is not that hard. I've made a table to act as a quick reference and to guide you. If you still can't create the room, I can't help you, but someone else can.
Skip the instructions in italics if a certain ruleset is not required.
If you are using custom rulesets, you will need to download the rules into <nullpomino folder>/config/rule/. The HD Team League rules can be found at the bottom of the first post in this thread1. Choose the ruleset from Options->Change rule2. Click new room
3. Click customize
4. Ensure rule lock is on5. Change the options to match those in the chart
6. Change the number of players, hurry up time, and the name of the room if desired
7. Click OK
Tip: Once you've created the room, go to the preset tab, choose a number and save it. Next time, you will only need to load that preset to restore the settings.
np wiki room settings