Hey Tamara, welcome to the forum.
There's several options for doing this. If you want a single thought per task, there's detail on the formatting required for importing thoughts from an Excel spreadsheet on page 216 of the PersonalBrain 6 User Guide. However, you can't add check boxes to thoughts. The best way to accomplish this is to create a thought type as Task, and attach a box as the Thought Icon. You can also set a thought type for completed items, with a thought icon as a checked box. When you enter a task, you would assign the first Thought Type, when you are done, you can change it to Completed.You will also have to set due dates after the import manually (from the calendar tab). There is no way to import task events. Second way is to create a thought for your tasks and add the separate tasks in the notes. You should be able to paste the table as plain text and it will paste a list (depending on the format of your table). It should prompt you if you want to paste as plain text when you paste the information in, however, if it doesn't, you can go to Options > Preferences > Advanced, and check the Copy/cut/paste notes as text always. Once you've pasted it you can go back and uncheck the box. Once it's in the notes you can add checkboxes. The downside of this is you can't set individual calendar events for the task. Third way is just create a thought for your tasks and add the spreadsheet as an attachment. The way I do it is I create thoughts for projects, and within the project, add notes with checkboxes for the tasks within the project. I also add events for due dates. When I'm going to work on something today I add a @today tag (I have that tag pinned to the top of my plex). This works well for me, but the best way is to try different things and see what works best for your.
Java SE 6