Grape Cordial

Don't know whether this is going to taste right or even whether I made it right, but if you don't give it a go you'll never know will you!?

My Dad gave me all the grapes from his vines (he likes the vines not the grapes!) to see whether I could do anything with them. I'm not good at the wine thing so I thought I'd do cordial. I put all the grapes in my tub then bashed them with a rolling pin to release the juice. Then I strained them for a few hours. I measured the juice then added suger at a rate of 700g per litre of juice, added both to a pan, brought slowly to the boil then bottled in sterlised jars. I'll let you know what it tastes like, although I have to say the colour isn't particularly appealling.