hey welcome. not sure how to ask for it in germany, but a couple things
1.) herb is sold by grams, and increments of ounces/pounds/kilos depending on where you live for ex. 1/8 of an ounce 1/4 of an ounce 1/2....quarter pound and so on.
2.) there are many threads on here about cooking in the recipe section.
3.) for medicinal, invest in a vaporizer. also buy a glass pipe small enough for your pocket/purse, and/or a bong or bubbler for home.
4.) because you are new to herb, half a bowl or a bowl will be enough for a while, but tolerance builds quick. one hit on the vapor will be quite enough. too many hits (and this comes from exp) will put you in heaven without you realizing it, so vap easy at first.
5.) do not smoke around your three year old. not that it is particularly bad for him/her but you dont want them knowing about "drugs" when they are that young. but vaporizing is ok to do, as long as they dont focus for to long on what you are doing.
glass pipes/bong/bubblers are pretty much the same, but i would recomend getting a roor bong, a vapor brothers vaporizer, and learn how to roll jay's. happy tokin