New to SF

[taita]

hello,
i´m new to SF. I´ve been trying for 2 times, but i can´t put it in.
My cock it´s longer than my hole. So i thought that was easy to put it because it passes my hole. But i can´t put it in. WHen i press the cock head to my hole, it don´t stay there. Only gets out. But my cock dimensions are perfect to put it in.

any advise

thanks
taita