as far as i know you can vote for a max of 30 witnesses, or at least that is what it tells me when i click on it...i was also trying to ask questions about this earlier to try and understand more.. i guess witnesses run the servers that this wonderful website operates on? from what i understand.. so in that case YES they are VERY important and vital to success of steemit! :) u just click on 'vote for witnesses' on the top right in the menu there and then upvote them and the arrow will turn blue after you vote them,.. i voted for people who i liked or thought were very active members of the community , and i even voted for some who i had no idea who they were too!
updated here is the link that I was given a day ago to give me some more info on witnesses and what they do :) https://steemit.com/steemit-guides/@pfunk/a-full-steemit-user-s-guide-to-steem-witnesses
Oh so I click on the 3 lines in the right hand corner scroll down to vote for witness, yay that was easy. Wow you get to chose 30, that is a lot, I will got have a look and see who appeals to me. Thank you @doitvoluntarily that was a massive help :)
yes you get lots of choices! haha
Now it depends who pays me the most money for my vote hahah