Question about drinking for the first time?

okay, well i'm 18 y/o and never drank before......i decided i want to go drink with my bf. well were gonna be safe n everything....were goin to a hotel and spendin the nite so were not drivin or ne thing......we just want to have a good time with the 2 of us.....not really havin a goal of gettin drunk jus drinkin to have a good time......well hes drank in the past but not for awhile....im kinda nervous tho.........like what should i drink.....im scared cuz ive heard of alcohol poisining n stuff and i dont want to get hurt......im 5'5" and about 120 lb.........we got some smirnoffs n stuff.....is that okay to drink the first time....how much is okay to drink for my height and weight without getting hurt? please help, i'm scared. i really wanna drink but i want to b safe. thanxx!