The first step to creating a custom scheduled task is to create a "command" to be used with it. To create a command, follow these steps:
1. Go to Advanced > Commands > Create Command in your Multicraft panel.
2. Enter the "Name" you want for this command. This is how it will be listed in the Scheduled Tasks page Command list.
3. Leave the Required Role, Prerequisite, Chat, and Response boxes empty (unless you need to use them).
4. Enter the command you want in the "Run" box without a forward slash / (it will be run as if from the console).
5. Click "Create" and you have your command created.
Now to create the actual Scheduled Task itself.
1. Go to Advanced> Scheduled Tasks > New Task from your Multicraft panel.
2. Enter the "Name" you want for the task.
3. Enter the "Scheduled Time" you want for it. If you wish for it to run at an interval, just check the "Interval" box, and this setting will set the first time the task will run.
4. Select the "Command" you created earlier, or any of the pre-defined commands.
5. The "Arguments" setting is basically what will allow you to set multiple variations of a single command. For example, if you have a command to say something on the server (say), filling in this arguments box will basically add things after the command itself (say Some Argument). It allows you to create only one command, but have multiple scheduled tasks with different arguments for the command, thus keeping things a bit more organized. You can read more about how to set it up properly here: http://www.multicraft.org/site/docs?view=howto#commands
6. Hit "Create" and you are done. Now you just have to wait for the scheduled time you set the task to run at and monitor your server/console to see if it ran successfully.