I am 25 year male. I can hold the plank position for 1 min. How many times should I repeat that? What should be the interval? I am a beginner so please enlighten me with the correct info so that I won't end up in the hospital by overdoing things.
There is no training system that works for everyone, but the one that I tend do and which works for me is to do three sets of planks a day. Using a timer, hold the plank for a minute (or about 10 seconds less than how long you can stay up) and then rest. To know about how much rest you need and to work your core evenly, do a side plank (as illustrated here) on your left and then your right side for half the time you do your forward plank. You can choose to go back to your plank right after your side plank, or let your core rest and do it later in the day.
I would aim to do three sets a day, two or three days in a row before taking a rest day to allow your muscles to repair. Once the one minute plank gets easy, slowly increment how long you stay up, or challenge yourself with a variation of the plank (as seen here).
To address your fear of ending up in the hospital, it's highly unlikely that planks will wind you up there. Moderate discomfort is good while doing your plank: it means that your muscles are working. Even if you try to hold it too long, the worst thing that can usually happen is your core "collapsing" (giving out) and ending up lying down on the ground. Unless you have severe pain over the course of multiple days, there shouldn't be any reason to panic over planks.
Best of luck in your training!