You'll get lots of ideas and help from this site. When I started out, the single biggest tool that helped me was a picture of all the activities for the whole year laid out.
As a committee member, I was often frustrated because the then-president (nice person, but disorganized) never presented the big picture. We'd have an event planned for May, so maybe it didn't warrant much discussion at the February Board meeting. But then later we'd discover a deadline for a decision or vote was needed before the March meeting. You can't afford to just look 30-60 days out.
I tried a "real" calendar, but that didn't work for me. I needed to see the whole list - and it kept growing. What I ended up using was a spreadsheet (Excel), with the following columns:
date, event, previous date, notes/comments. And the date field was formatted so it showed the day - like Tues, Nov. 1. (You could also do this in a table in Word, but I think a spreadsheet is easier.)
This list included school holidays, school events, major tests, PTO activities, financial deadlines, when fundraisers began and ended, etc. The list changed constantly, but the fact that it could be so dynamic made it a great planning tool. And the next year, I'd just move all the dates to the "previous year" column and have a great template to start filling in with current data.
Format-wise, I skipped a couple spaces between months. If something didn't have a date, I'd just stick it in the month it usually occured and note last year's date. You can put in milestones, too. So, say your Spring auction is in May. Maybe "start soliciting" company donations goes in January. (You don't want EVERY committee task on this list, but maybe the really important ones.)
This really helped us in planning. It showed things like gaps where that events might fit nicely, testing periods where extra volunteers might be needed or extracurricular activities should be reduced.
We're all here to help you. Just keep reading and asking questions and sharing back what works.