Day 1 of your cycle is the first day of your period; the last day of that cycle is the day before your next period starts. In order to figure out how long your cycle is, you will need to go through a complete cycle and keep track of the days. The length of each cycle could vary by a few days. hope this helps.
the first day of your cycle is the first day of bleeding. So if your period is from March 13-March 17 then day one of your cycle is March 13. Thus, the last day of your cycle is the day before the bleeding starts.
So lets say that you start bleeding on March 13, then you go the whole month and start bleeding again on April 12. Then your menstral cycle is from March 13-April 11, just count the days (of course that is only an example).
HOWEVER, ovulation calculatiors are not super great, although decent if you are not doing anything else. It sounds like you are just starting, so let me give you what I know.
Basal Body Temp (BBT)- This is a temp you take first thing in the morning right when you wake up before you move at all. You should use a basal body thermometer (has 2 digits after decimal). You need to always take this temp at the same time of day, EX: 6 am everyday, variations in time will effect your temp. You chart your temps (look at www.fertilityfriend.com). You can thensee patterns, in general you temp before Ovulation (O) is low and temp after O is higher. You can tell the exact day you ovulate because your temp will spike the day after ovulation.
OPK's- these are ovulation predictor test kits, you pee on them and they tell you when about 24 hours before you ovulate. For these to be considered positive the two lines must be eqally as dark, or the test line darker than the control line. You pee on these between 11am and 8pm, and it pays to be alittle dehydrated.
CP and CM- cervical position and cervical mucus. If you arent too squemish, you can use a finger inserted into the vagina to test these. AFter a few weeks you will start to understand what it means. Sometimes your cervix will be high and hard to reach, other times it will be low and right there at the front. Cervical mucus is actual mucus right around your cervix, This mucus can be noted extrernally on the Vulva, but other people like me after to go fishing for it. Cervical mucus varies from dry to creamy to watery to eggwhite cervical mucus.
Using a combination of these things is the best way to determine when you ovulate, because ovulation calculators just find the middle fo your cycle, and most women dont ovulate on that day. You shoul use a combination of all these methods. www.fertilityfriend.com is a great website that is FREE and you put in your information and it charts it all out beautifully, it also tells you exactly when you ovulated based on the info you give it. Take a look at my chart using the link below to see how it works.
Do some internet searches on the info I gave you above, or feel free to ask us more questions, we always love to help and share all we have learned!!
My Chart for an example:
http://www.fertilityfriend.com/home/1995f3