How To Loosen Vagina During Intercourse?

we r married a year and now we r trying for a baby. since we r beginners we dnt know the exact positions for sex. many times we tried but couldnt make it to even half penetration. we r upset bcoz of that. we r shy to ask anyone. he s telling my vagina is tight for his penis. what should we do for a better penetration to conceive?