Although there will be missions pre-made for everyone and some village specific, we do encourage you to try and make your own. Before you make your missions you should keep this in mind...
There are also D-rank missions, the lowest classification a mission can receive. These missions are usually assigned to genin. Naruto Uzumaki describes D-rank missions as not being actual missions as they deal with tasks as simple as finding missing pets and weeding a garden. Minimal danger is seen on these missions.
There are also C-rank missions. These missions are usually assigned to chūnin, or in some cases, genin. Assignments include bodyguard duty and hunting wild animals, all of which will likely pose some risk to the ninja. C-Rank missions will never have other ninja activity but this does not mean some bandits or criminals will be involved. There is slight risk of danger, but nothing a cool ninja like you cant handle!
There are also B-rank missions. These missions are usually assigned to jōnin or chūnin. Assignments can involve spying or assassinations, and ninja are expected to go up against enemy ninja during the course of the mission. Missions like these will have other ninja activity and you will run the risk of danger.
Travel around, find information, go behind enemy lines, assassinate powerful people or even invade a location. The things I just mentioned is the start of it. Imagine what people could ask you to do? These missions are absolutely dangerous. The risk of dying is high.
Missions can also be classified as S-rank, these are the highest paying and most dangerous type of mission a ninja can go on. These missions are exclusively assigned to highly skilled jōnin or large squads of ninja There is nothing more dangerous than this type of mission only the greatest or stupidest ninja accept these.