Lately we dicussed to use hair conditioner on real wool, if you want it to mellow out and lose the "spring". Careful, it may work really well grin maybe try it on a swatch first.
But it depends on what yarn you used. Acrylic may be harder to "tame" than wool.
In any case: wash it (with or without detergent?), lay it flat to dry and maybe even block it. You can repeat the procedure as often as you want to try different stretches.
oh, and count your stitches to compare with the photos. Sometimes the photos are just simmilar to the pattern given and not really the same. That can be very annoying (especially when the differences are very visible) because you do not get what you were intending to get.