Heel
I agree with Harley and r.w. Make sure your centerboard is down! If you're in higher winds and it starts to feel uncomfortable, uncleat the main sheet and hold it in one hand (don't wrap it around your hand, just keep a grip on it) and when you start to round up, ease the sheet. Probably a couple of feet at first, then you should start to get the feel of it and be able to balance with smaller adjustments. Remember the boat can only convert so much power into forward movement; if you've got the tiller pulled up hard just to keep the boat straight, you have your main trimmed in too much - it's like driving with one foot on the gas and one on the brake. Ease the sheet to dump some of the power out of the main, the boat will settle down, it won't feel as exciting but you'll actually be going faster. Having the rail in the water is slow.If you find you can't bring the main in at all, and it's constantly flogging, you have too much wind and you need to reef.I wouldn't worry about capsizing, as r.w. said, she'll heel, you'll have less rudder in the water, then the main will overpower the rudder, and she'll round up into the wind, she'll flatten out, you can fall off the wind a bit and start again.Have fun!Kevin