Favourite character for the begin?

I'm looking for good champions and line to begin playing. My friends told to me to take bot line, but I don't know how to play. I need the best character to begin playing.

It depends on your play style in general. If you're a passive player, but like to heal/support your partner..then support bottom lane is ideal. It's simple, and can be tedious. That would be the easiest route. Then middle lane is usually 1v1 with a character that's AP focused(magic) or could even do whatever the norm is nowadays.

As a new player i would start by playing support, that way you can have an understanding of the game and will not get as punished as you would if you were playing a solo lane, another lane you can practice is jungle, since its a crucial role for your team and will help you out learning paths, objectives and map awareness, knowing when to gank, when to step aside and when to just leave it be and get back. A good champion to start as support would be soraka, sona, nami and yuumi, all of them have decent cc and help you out with healing in case you go to far and get punished, it will offer you and your ADC some sustain.
As for junglers, a few ez picks to start would be fast clears and useful ganks, i would try rammus, amumu, warwick since both have decent clears and decent cc for ganks.
In the end its up to you if you like them and if you enjoy playing them.

it depends on your skills but if you're new in the game best option is master yi or sett :=)

depends of play style but i recommend you mundo its tanky and r gets hp

Definitely bruisers/tanky champs. Tryndamere was ultra easy when I first started though because of the R bait.